Cabin fuselage structural design with engine installation and control system

Science.gov (United States)

Balakrishnan, Tanapaal; Bishop, Mike; Gumus, Ilker; Gussy, Joel; Triggs, Mike

1994-01-01

Design requirements for the cabin, cabin system, flight controls, engine installation, and wing-fuselage interface that provide adequate interior volume for occupant seating, cabin ingress and egress, and safety are presented. The fuselage structure must be sufficient to meet the loadings specified in the appropriate sections of Federal Aviation Regulation Part 23. The critical structure must provide a safe life of 10(exp 6) load cycles and 10,000 operational mission cycles. The cabin seating and controls must provide adjustment to account for various pilot physiques and to aid in maintenance and operation of the aircraft. Seats and doors shall not bind or lockup under normal operation. Cabin systems such as heating and ventilation, electrical, lighting, intercom, and avionics must be included in the design. The control system will consist of ailerons, elevator, and rudders. The system must provide required deflections with a combination of push rods, bell cranks, pulleys, and linkages. The system will be free from slack and provide smooth operation without binding. Environmental considerations include variations in temperature and atmospheric pressure, protection against sand, dust, rain, humidity, ice, snow, salt/fog atmosphere, wind and gusts, and shock and vibration. The following design goals were set to meet the requirements of the statement of work: safety, performance, manufacturing and cost. To prevent the engine from penetrating the passenger area in the event of a crash was the primary safety concern. Weight and the fuselage aerodynamics were the primary performance concerns. Commonality and ease of manufacturing were major considerations to reduce cost.

14 CFR 23.841 - Pressurized cabins.

Science.gov (United States)

2010-01-01

... probable failure or malfunction in the pressurization system. (b) Pressurized cabins must have at least the following valves, controls, and indicators, for controlling cabin pressure: (1) Two pressure relief valves... compressor or to divert airflow from the cabin if continued rotation of an engine-driven cabin compressor or...

Optimization of actuator arrays for aircraft interior noise control

Science.gov (United States)

Cabell, R. H.; Lester, H. C.; Mathur, G. P.; Tran, B. N.

1993-01-01

A numerical procedure for grouping actuators in order to reduce the number of degrees of freedom in an active noise control system is evaluated using experimental data. Piezoceramic actuators for reducing aircraft interior noise are arranged into groups using a nonlinear optimization routine and clustering algorithm. An actuator group is created when two or more actuators are driven with the same control input. This procedure is suitable for active control applications where actuators are already mounted on a structure. The feasibility of this technique is demonstrated using measured data from the aft cabin of a Douglas DC-9 fuselage. The measured data include transfer functions between 34 piezoceramic actuators and 29 interior microphones and microphone responses due to the primary noise produced by external speakers. Control inputs for the grouped actuators were calculated so that a cost function, defined as a quadratic pressure term and a penalty term, was a minimum. The measured transfer functions and microphone responses are checked by comparing calculated noise reductions with measured noise reductions for four frequencies. The grouping procedure is then used to determine actuator groups that improve overall interior noise reductions by 5.3 to 15 dB, compared to the baseline experimental configuration.

Investigating the air quality in aircraft cabins

International Nuclear Information System (INIS)

Nilsen, Steinar K.

2002-01-01

In recent years, there has been increasing concern about the air quality in aircraft cabins and its effects on health and safety for crew and passengers. Some of the major worries are risk of communication of infectious diseases, high incidence of respiratory diseases caused by low air moisture, and increased concentration of carbon dioxide from exhaled air due to the cabin air being recirculated. It also happens that fumes and gases enter the cabin by way of the ventilation system. This article describes the EU-funded research programme called CabinAir. The project aims to: (1) establish the current level of air quality in aircraft cabins, (2) establish the relationship between cabin air quality and the performance of environmental control and filtration systems, the air distribution, the energy consumption and the environmental impact of fuel burn. (3) develop new designs and technical solutions to improve the environmental control system and cabin air distribution/control systems, (4) optimise air quality in the cabin and minimise fuel consumption and environmental impacts, (5) develop performance specifications for the components, (6) draft European Pre-Normative Standards

Individual and collective climate control in aircraft cabins

NARCIS (Netherlands)

Jacobs, P.; Gids, W.F. de

2006-01-01

A new concept for aircraft cabin climatisation has been developed in which the seat is the main Indoor Air Quality (IAQ) and temperature control system for the passengers containing provisions for local supply and local exhaust of air. Direct supply of clean outside air in the breathing zone,

An innovative HVAC control system: Implementation and testing in a vehicular cabin.

Science.gov (United States)

Fojtlín, Miloš; Fišer, Jan; Pokorný, Jan; Povalač, Aleš; Urbanec, Tomáš; Jícha, Miroslav

2017-12-01

Personal vehicles undergo rapid development in every imaginable way. However, a concept of managing a cabin thermal environment remains unchanged for decades. The only major improvement has been an automatic HVAC controller with one user's input - temperature. In this case, the temperature is often deceiving because of thermally asymmetric and dynamic nature of the cabins. As a result, the effects of convection and radiation on passengers are not captured in detail what also reduces the potential to meet thermal comfort expectations. Advanced methodologies are available to assess the cabin environment in a fine resolution (e.g. ISO 14505:2006), but these are used mostly in laboratory conditions. The novel idea of this work is to integrate equivalent temperature sensors into a vehicular cabin in proximity of an occupant. Spatial distribution of the sensors is expected to provide detailed information about the local environment that can be used for personalised, comfort driven HVAC control. The focus of the work is to compare results given by the implemented system and a Newton type thermal manikin. Three different ambient settings were examined in a climate chamber. Finally, the results were compared and a good match of equivalent temperatures was found. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application and Simulation of Fuzzy Neural Network PID Controller in the Aircraft Cabin Temperature

Directory of Open Access Journals (Sweden)

Ding Fang

2013-06-01

Full Text Available Considering complex factors of affecting ambient temperature in Aircraft cabin, and some shortages of traditional PID control like the parameters difficult to be tuned and control ineffective, this paper puts forward the intelligent PID algorithm that makes fuzzy logic method and neural network together, scheming out the fuzzy neural net PID controller. After the correction of the fuzzy inference and dynamic learning of neural network, PID parameters of the controller get the optimal parameters. MATLAB simulation results of the cabin temperature control model show that the performance of the fuzzy neural network PID controller has been greatly improved, with faster response, smaller overshoot and better adaptability.

Noise mapping inside a car cabin

DEFF Research Database (Denmark)

Knudsen, Kim; Sjøj, Sidsel Marie Nørholm; Jacobsen, Finn

The mapping of noise is of considerable interest in the car industry where a good noise mapping can make it much easier to identify the sources that generate the noise and eventually reduce the individual contributions to the noise. The methods used for this purpose include delay-and-sum beamform......The mapping of noise is of considerable interest in the car industry where a good noise mapping can make it much easier to identify the sources that generate the noise and eventually reduce the individual contributions to the noise. The methods used for this purpose include delay......-and-sum beamforming and spherical harmonics beamforming. These methods have a poor spatial esolution at low frequencies, and since much noise generated in cars is dominated by low frequencies the methods are not optimal. In the present paper the mapping is done by solving an inverse problem with a transfer matrix...

Muscle oxygenation, EMG, and cardiovascular responses for cabin attendants vs. controls

DEFF Research Database (Denmark)

Sandfeld, Jesper; Larsen, Lisbeth Højkjær; Crenshaw, Albert Guy

2013-01-01

The goal was to investigate the effect of acute moderate hypobaric exposure on the physiological responses to sustained contractions (local) and light to moderate dynamic exercise (systemic) for cabin attendants (CAB) and a matched control group (CON)....

Exploitation Strategies of Cabin and Galley Thermal Dynamics

OpenAIRE

Schlabe, Daniel; Zimmer, Dirk; Pollok, Alexander

2017-01-01

The thermal inertia of aircraft cabins and galleys is significant for commercial aircraft. The aircraft cabin is controlled by the Environment Control System (ECS) to reach, among other targets, a prescribed temperature. By allowing a temperature band of ± 2 K instead of a fixed temperature, it is possible to use this thermal dynamic of the cabin as energy storage. This storage can then be used to reduce electrical peak power, increase efficiency of the ECS, reduce thermal cooling peak power...

Orbiter CCTV video signal noise analysis

Science.gov (United States)

Lawton, R. M.; Blanke, L. R.; Pannett, R. F.

1977-01-01

The amount of steady state and transient noise which will couple to orbiter CCTV video signal wiring is predicted. The primary emphasis is on the interim system, however, some predictions are made concerning the operational system wiring in the cabin area. Noise sources considered are RF fields from on board transmitters, precipitation static, induced lightning currents, and induced noise from adjacent wiring. The most significant source is noise coupled to video circuits from associated circuits in common connectors. Video signal crosstalk is the primary cause of steady state interference, and mechanically switched control functions cause the largest induced transients.

Case Studies in Crewed Spacecraft Environmental Control and Life Support System Process Compatibility and Cabin Environmental Impact

Science.gov (United States)

Perry, J. L.

2017-01-01

Contamination of a crewed spacecraft's cabin environment leading to environmental control and life support system (ECLSS) functional capability and operational margin degradation or loss can have an adverse effect on NASA's space exploration mission figures of merit-safety, mission success, effectiveness, and affordability. The role of evaluating the ECLSS's compatibility and cabin environmental impact as a key component of pass trace contaminant control is presented and the technical approach is described in the context of implementing NASA's safety and mission success objectives. Assessment examples are presented for a variety of chemicals used in vehicle systems and experiment hardware for the International Space Station program. The ECLSS compatibility and cabin environmental impact assessment approach, which can be applied to any crewed spacecraft development and operational effort, can provide guidance to crewed spacecraft system and payload developers relative to design criteria assigned ECLSS compatibility and cabin environmental impact ratings can be used by payload and system developers as criteria for ensuring adequate physical and operational containment. In additional to serving as an aid for guiding containment design, the assessments can guide flight rule and procedure development toward protecting the ECLSS as well as approaches for contamination event remediation.

Prediction of car cabin environment by means of 1D and 3D cabin model

Science.gov (United States)

Fišer, J.; Pokorný, J.; Jícha, M.

2012-04-01

Thermal comfort and also reduction of energy requirements of air-conditioning system in vehicle cabins are currently very intensively investigated and up-to-date issues. The article deals with two approaches of modelling of car cabin environment; the first model was created in simulation language Modelica (typical 1D approach without cabin geometry) and the second one was created in specialized software Theseus-FE (3D approach with cabin geometry). Performance and capabilities of this tools are demonstrated on the example of the car cabin and the results from simulations are compared with the results from the real car cabin climate chamber measurements.

Controlling active cabin suspensions in commercial vehicles

NARCIS (Netherlands)

Evers, W.J.E.; Besselink, I.J.M.; Teerhuis, A.P.; Knaap, van der A.C.M.; Nijmeijer, H.

2009-01-01

The field of automotive suspensions is changing. Semi-active and active suspensions are starting to become viable options for vehicle designers. Suspension design for commercial vehicles is especially interesting given its potential. An active cabin suspension for a heavy-duty truck is considered,

Prediction of car cabin environment by means of 1D and 3D cabin model

Directory of Open Access Journals (Sweden)

Jícha M.

2012-04-01

Full Text Available Thermal comfort and also reduction of energy requirements of air-conditioning system in vehicle cabins are currently very intensively investigated and up-to-date issues. The article deals with two approaches of modelling of car cabin environment; the first model was created in simulation language Modelica (typical 1D approach without cabin geometry and the second one was created in specialized software Theseus-FE (3D approach with cabin geometry. Performance and capabilities of this tools are demonstrated on the example of the car cabin and the results from simulations are compared with the results from the real car cabin climate chamber measurements.

78 FR 52848 - Occupational Safety and Health Standards for Aircraft Cabin Crewmembers

Science.gov (United States)

2013-08-27

... air quality issues; food/beverage carts; and ergonomics. OSHA's noise, bloodborne pathogens, and... exposure, cabin air quality, food and beverage cart and ergonomic issues are not being considered at this... comments from the National Institute for Occupational Safety and Health that cited several studies it...

Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

Science.gov (United States)

Fuller, C. R.

1998-01-01

The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

The Fate of Trace Contaminants in a Crewed Spacecraft Cabin Environment

Science.gov (United States)

Perry, Jay L.; Kayatin, Matthew J.

2016-01-01

Trace chemical contaminants produced via equipment offgassing, human metabolic sources, and vehicle operations are removed from the cabin atmosphere by active contamination control equipment and incidental removal by other air quality control equipment. The fate of representative trace contaminants commonly observed in spacecraft cabin atmospheres is explored. Removal mechanisms are described and predictive mass balance techniques are reviewed. Results from the predictive techniques are compared to cabin air quality analysis results. Considerations are discussed for an integrated trace contaminant control architecture suitable for long duration crewed space exploration missions.

The Cabin Crew Blues. Middle-aged Cabin Attendants and Their Working Conditions

Directory of Open Access Journals (Sweden)

Ann Bergman

2015-12-01

Full Text Available This article examines how an airline company uses the labor of a group of middle-aged cabin attendants in an industry increasingly characterized by deregulation and competiveness. The study was based on in-depth interviews with seven women, all with between 24 and 30 years of work experience as cabin attendants. The article focuses on the women’s working conditions and well-being and the analysis reveals three key aspects—intensification of work, vulnerability, and aging—that affect the cabin attendants’ experiences and emotions in relation to the work. It is at the intersection of these three aspects that the cabin attendants’ concerns must be understood. The study’s findings indicated that positive emotions such as job satisfaction and commitment have diminished because of exploitative and otherwise poor working conditions. Taking the cabin attendants’ concerns as its point of departure, the article shows that there is a need to move away from a discussion about emotional labor toward a discussion of working conditions.

Active Structural Acoustic Control of Interior Noise on a Raytheon 1900D

Science.gov (United States)

Palumbo, Dan; Cabell, Ran; Sullivan, Brenda; Cline, John

2000-01-01

An active structural acoustic control system has been demonstrated on a Raytheon Aircraft Company 1900D turboprop airliner. Both single frequency and multi-frequency control of the blade passage frequency and its harmonics was accomplished. The control algorithm was a variant of the popular filtered-x LMS implemented in the principal component domain. The control system consisted of 21 inertial actuators and 32 microphones. The actuators were mounted to the aircraft's ring frames. The microphones were distributed uniformly throughout the interior at head height, both seated and standing. Actuator locations were selected using a combinatorial search optimization algorithm. The control system achieved a 14 dB noise reduction of the blade passage frequency during single frequency tests. Multi-frequency control of the first 1st, 2nd and 3rd harmonics resulted in 10.2 dB, 3.3 dB and 1.6 dB noise reductions respectively. These results fall short of the predictions which were produced by the optimization algorithm (13.5 dB, 8.6 dB and 6.3 dB). The optimization was based on actuator transfer functions taken on the ground and it is postulated that cabin pressurization at flight altitude was a factor in this discrepancy.

Effects of acoustic treatment on the interior noise levels of a twin-engine propeller aircraft - Experimental flight results and theoretical predictions

Science.gov (United States)

Beyer, T. B.; Powell, C. A.; Daniels, E. F.; Pope, L. D.

1984-01-01

In-flight noise level measurements were made within two cabin configurations of a general aviation business aircraft. The Fairchild Merlin IVC twin-engine aircraft was tested with bare walls and fiberglass insulation and in an executive trim configuration. Narrow-band and octave format data were subjected to analyses which permitted identification of the blade passage harmonics (BPH). Cabin noise level reductions (insertion losses) due to added insulation varied with position in the cabin, the BPH number, cabin pressure, and engine torque. The measurements were closely predicted using the propeller aircraft interior noise (PAIN) mode.

Sustainable development of cabins. An investigation of cabin owners' attitudes towards the environment and energy

International Nuclear Information System (INIS)

Velvin, Jan

2004-01-01

An investigation on private cabin owners in the three Buskerud (Norway) municipalities: Sigdal, Rollag and Hol. The main purpose has been to evaluate the state of local value-creation related to cabin tourism, energy and environmental aspects of the cabin-usage, and other conditions related to sustainable development. This report deals in specific with environment and energy questions concerning cabin owners, and their attitudes towards energy-saving measures. Results from the investigation show that the standard on facilities of cabins has increased, indicating that the energy consumption will rise accordingly. Income is the primary explanation factor in relation to energy consumption. More results are presented in the report (ml)

Design Concept for a Minimal Volume Spacecraft Cabin to Serve as a Mars Ascent Vehicle Cabin and Other Alternative Pressurized Vehicle Cabins

Science.gov (United States)

Howard, Robert L., Jr.

2016-01-01

The Evolvable Mars Campaign is developing concepts for human missions to the surface of Mars. These missions are round-trip expeditions, thereby requiring crew launch via a Mars Ascent Vehicle (MAV). A study to identify the smallest possible pressurized cabin for this mission has developed a conceptual vehicle referred to as the minimal MAV cabin. The origin of this concept will be discussed as well as its initial concept definition. This will lead to a description of possible configurations to integrate the minimal MAV cabin with ascent vehicle engines and propellant tanks. Limitations of this concept will be discussed, in particular those that argue against the use of the minimal MAV cabin to perform the MAV mission. However, several potential alternative uses for the cabin are identified. Finally, recommended forward work will be discussed, including current work in progress to develop a full scale mockup and conduct usability evaluations.

Effect of relative humidity and temperature control on in-cabin thermal comfort state: Thermodynamic and psychometric analyses

International Nuclear Information System (INIS)

Alahmer, A.; Omar, M.A.; Mayyas, A.; Dongri, Shan

2011-01-01

This manuscript discusses the effect of manipulating the Relative Humidity RH of in-cabin environment on the thermal comfort and human occupants' thermal sensation. The study uses thermodynamic and psychometric analyses, to incorporate the effect of changing RH along with the dry bulb temperature on human comfort. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect of relative humidity on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. The results show that changing the RH along with dry bulb temperature inside vehicular cabins can improve the air conditioning efficiency by reducing the heat removed while improving the Human comfort sensations as measured by the Predicted Mean Value PMV and the Predicted Percentage Dissatisfied PPD indices. - Highlights: → Investigates the effect of controlling the RH and dry bulb temperature on in-cabin thermal comfort and sensation. → Conducts the thermodynamic and psychometric analyses for changing the RH and temperature for in-cabin air conditioning. → Discusses a possible system implementation through an evaporative cooler design.

Active Noise Control for Dishwasher noise

Science.gov (United States)

Lee, Nokhaeng; Park, Youngjin

2016-09-01

The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

Risk factors for skin cancer among Finnish airline cabin crew.

Science.gov (United States)

Kojo, Katja; Helminen, Mika; Pukkala, Eero; Auvinen, Anssi

2013-07-01

Increased incidence of skin cancers among airline cabin crew has been reported in several studies. We evaluated whether the difference in risk factor prevalence between Finnish airline cabin crew and the general population could explain the increased incidence of skin cancers among cabin crew, and the possible contribution of estimated occupational cosmic radiation exposure. A self-administered questionnaire survey on occupational, host, and ultraviolet radiation exposure factors was conducted among female cabin crew members and females presenting the general population. The impact of occupational cosmic radiation dose was estimated in a separate nested case-control analysis among the participating cabin crew (with 9 melanoma and 35 basal cell carcinoma cases). No considerable difference in the prevalence of risk factors of skin cancer was found between the cabin crew (N = 702) and the general population subjects (N = 1007) participating the study. The mean risk score based on all the conventional skin cancer risk factors was 1.43 for cabin crew and 1.44 for general population (P = 0.24). Among the cabin crew, the estimated cumulative cosmic radiation dose was not related to the increased skin cancer risk [adjusted odds ratio (OR) = 0.75, 95% confidence interval (CI): 0.57-1.00]. The highest plausible risk of skin cancer for estimated cosmic radiation dose was estimated as 9% per 10 mSv. The skin cancer cases had higher host characteristics scores than the non-cases among cabin crew (adjusted OR = 1.43, 95% CI: 1.01-2.04). Our results indicate no difference between the female cabin crew and the general female population in the prevalence of factors generally associated with incidence of skin cancer. Exposure to cosmic radiation did not explain the excess of skin cancer among the studied cabin crew in this study.

Transport of expiratory droplets in an aircraft cabin.

Science.gov (United States)

Gupta, Jitendra K; Lin, Chao-Hsin; Chen, Qingyan

2011-02-01

The droplets exhaled by an index patient with infectious disease such as influenza or tuberculosis may be the carriers of contagious agents. Indoor environments such as the airliner cabins may be susceptible to infection from such airborne contagious agents. The present investigation computed the transport of the droplets exhaled by the index patient seated in the middle of a seven-row, twin-aisle, fully occupied cabin using the CFD simulations. The droplets exhaled were from a single cough, a single breath, and a 15-s talk of the index patient. The expiratory droplets were tracked by using Lagrangian method, and their evaporation was modeled. It was found that the bulk airflow pattern in the cabin played the most important role on the droplet transport. The droplets were contained in the row before, at, and after the index patient within 30 s and dispersed uniformly to all the seven rows in 4 minutes. The total airborne droplet fraction reduced to 48, 32, 20, and 12% after they entered the cabin for 1, 2, 3, and 4 min, respectively, because of the ventilation from the environmental control system. It is critical to predict the risk of airborne infection to take appropriate measures to control and mitigate the risk. Most of the studies in past either assume a homogenous distribution of contaminants or use steady-state conditions. The present study instead provides information on the transient movement of the droplets exhaled by an index passenger in an aircraft cabin. These droplets may contain active contagious agents and can be potent enough to cause infection. The findings can be used by medical professionals to estimate the spatial and temporal distribution of risk of infection to various passengers in the cabin. © 2010 John Wiley & Sons A/S.

Aeroacoustics of Flight Vehicles: Theory and Practice. Volume 2. Noise Control

Science.gov (United States)

1991-08-01

noisiness, Localization and Precedence The ability to determine the location of sound sources is one of the major benefits of having a binaural hearing... binaural hearing is commonly called the Haas. or precedence, effect (ref. 16). This refers to the ability to hear as a single acoustic event the...propellers are operated at slightly different rpm values, beating interference between the two sources occurs, and the noise level in the cabin rises and

Low-Frequency Noise Reduction by Earmuffs with Flax Fibre-Reinforced Polypropylene Ear Cups

Directory of Open Access Journals (Sweden)

Linus Yinn Leng Ang

2018-01-01

Full Text Available Soldiers and supporting engineers are frequently exposed to high low-frequency (<500 Hz cabin noise in military vehicles. Despite the use of commercial hearing protection devices, the risk of auditory damage is still imminent because the devices may not be optimally customised for such applications. This study considers flax fibre-reinforced polypropylene (Flax-PP as an alternative to the material selection for the ear cups of commercial earmuffs, which are typically made of acrylonitrile butadiene styrene (ABS. Different weaving configurations (woven and nonwoven and various noise environments (pink noise, cabin booming noise, and firing noise were considered to investigate the feasibility of the proposed composite earmuffs for low-frequency noise reduction. The remaining assembly components of the earmuff were kept consistent with those of a commercial earmuff, which served as a benchmark for results comparison. In contrast to the commercial earmuff, the composite earmuffs were shown to be better in mitigating low-frequency noise by up to 16.6 dB, while compromising midfrequency acoustical performance. Consequently, the proposed composite earmuffs may be an alternative for low-frequency noise reduction in vehicle cabins, at airports, and at construction sites involving heavy machineries.

Experimental Study of Airborne Contaminant Migration in an Aircraft Cabin Model

Science.gov (United States)

Poussou, Stephane; Sojka, Paul; Plesniak, Michael

2007-11-01

The cabin air ventilation system in wide body jetliners is designed to provide a comfortable and controlled environment for passengers. Inside the cabin, the air flows continuously from overhead vents into sidewall exhausts, forming a circular pattern designed to minimize cross flow between adjacent seat rows. However, spreading of gaseous or particulate contaminants is possible when flight attendants or passengers walk along an aisle, perturbing the ventilation flow. Such unsteady flow perturbations have been found to alter the cabin air distribution and quality. A better fundamental understanding of the turbulent transport phenomena is needed to improve air quality monitoring and control systems and to validate numerical simulations. The velocity field in a 15:1 model of a simplified aircraft cabin is probed to investigate the wake of a rectangular body moving through a steady two-dimensional flow at a Reynolds number (based on body height) of the order of 50,000. Planar Laser Induced Fluorescence is used to visualize wake structure and scalar contaminant transport. The interaction between the wake and the ventilation flow is measured with PIV. The data are compared to numerical studies of cabin airflows in the literature.

Light aircraft sound transmission studies - Noise reduction model

Science.gov (United States)

Atwal, Mahabir S.; Heitman, Karen E.; Crocker, Malcolm J.

1987-01-01

Experimental tests conducted on the fuselage of a single-engine Piper Cherokee light aircraft suggest that the cabin interior noise can be reduced by increasing the transmission loss of the dominant sound transmission paths and/or by increasing the cabin interior sound absorption. The validity of using a simple room equation model to predict the cabin interior sound-pressure level for different fuselage and exterior sound field conditions is also presented. The room equation model is based on the sound power flow balance for the cabin space and utilizes the measured transmitted sound intensity data. The room equation model predictions were considered good enough to be used for preliminary acoustical design studies.

Determination of thermal and acoustic comfort inside a vehicle's cabin

Science.gov (United States)

Ene, Alexandra; Catalina, Tiberiu; Vartires, Andreea

2018-02-01

Thermal and acoustic comfort, inside a vehicle's cabin, are highly interconnected and can greatly influence the health of the passengers. On one hand, the H.V.A.C. system brings the interior air parameters to a comfortable value while on the other hand, it is the main source of noise. It is an intriguing task to find a balance between the two. In this paper, several types of air diffusers were used in order to optimize the ratio between thermal and acoustic interior comfort. Using complex measurements of noise and thermal comfort parameters we have determined for each type of air diffuser the sound pressure level and its impact on air temperature and air velocity.

A Lightweight Loudspeaker for Aircraft Communications and Active Noise Control

Science.gov (United States)

Warnaka, Glenn E.; Kleinle, Mark; Tsangaris, Parry; Oslac, Michael J.; Moskow, Harry J.

1992-01-01

A series of new, lightweight loudspeakers for use on commercial aircraft has been developed. The loudspeakers use NdFeB magnets and aluminum alloy frames to reduce the weight. The NdFeB magnet is virtually encapsulated by steel in the new speaker designs. Active noise reduction using internal loudspeakers was demonstrated to be effective in 1983. A weight, space, and cost efficient method for creating the active sound attenuating fields is to use the existing cabin loudspeakers for both communication and sound attenuation. This will require some additional loudspeaker design considerations.

Comparison of different decontaminant delivery methods for sterilizing unoccupied commercial airliner cabins

Energy Technology Data Exchange (ETDEWEB)

Chen, Xi; Chen, Qingyan [National Air Transport Center of Excellence for Research in the Intermodal Transport Environment (RITE), School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47905 (United States)

2010-09-15

Effective decontamination is crucial if an airliner cabin is contaminated by biological contaminants, such as infectious disease viruses or intentionally released biological agents. This study used computational fluid dynamics (CFD) method as a tool and vaporized hydrogen peroxide (VHP) as an exemplary decontaminant and Geobacillus stearothermophilus spores as a simulant contaminant to investigate three VHP delivery methods for sterilizing two different airliner cabins. The CFD first determined the airflow and the transient distributions of the contaminant and decontaminant in cabins. Auxiliary equations were implemented into the CFD model for evaluating efficacy of the sterilization process. The improved CFD model was validated by the measured airflow and simulated contaminant distributions obtained from a cabin mockup and the measured efficacy data from the literature. The three decontaminant delivery methods were (1) to supply the mixed VHP and air through the environmental control system of a cabin, (2) to send mixed VHP and air through a front door and to extract them from a back door of a cabin, and (3) to send directly VHP to a cabin and enhance the mixing with air in the cabin by fans. The two air cabins studied were a single-aisle and a twin-aisle airliner one. The results show that the second decontaminant delivery method (displacement method) was the best because the VHP distributions in the cabins were most uniform, the sterilization time was moderate, and the corrosion risk was low. The method displaced the existing air by the air/disinfectant solution, rather than dispersive mixing as the other two methods. (author)

The noise factor in railway locomotives.

Science.gov (United States)

Rotter, T

1982-09-01

This article concerns the problem of acoustic work conditions on railway locomotives. The objective results of sonometric surveys in locomotive cabins are compared with subject data received from locomotive crews obtained by means of a specific questionnaire 'The Subjective Estimation of Noise'. The analysis touched 9 type of locomotives; steam, diesel and electric engines. We asked drivers of different age groups and with varying lengths of professional service for their opinions The aim of the investigation was to determine the following points: 1. to analyse the drivers' subjective estimation of the noise in the locomotive cabins; 2. to define length of time for which the driver remains under the influence of the noise after finishing work; 3. to investigate the question of perception and understanding of sounds and vocal signals used in the locomotive. These problems are a small part of the general plan to improve work conditions on the Polish National Railways.

Determination of thermal and acoustic comfort inside a vehicle’s cabin

Directory of Open Access Journals (Sweden)

2018-01-01

Full Text Available Thermal and acoustic comfort, inside a vehicle’s cabin, are highly interconnected and can greatly influence the health of the passengers. On one hand, the H.V.A.C. system brings the interior air parameters to a comfortable value while on the other hand, it is the main source of noise. It is an intriguing task to find a balance between the two. In this paper, several types of air diffusers were used in order to optimize the ratio between thermal and acoustic interior comfort. Using complex measurements of noise and thermal comfort parameters we have determined for each type of air diffuser the sound pressure level and its impact on air temperature and air velocity.

Multi-parameter decoupling and slope tracking control strategy of a large-scale high altitude environment simulation test cabin

Directory of Open Access Journals (Sweden)

Li Ke

2014-12-01

Full Text Available A large-scale high altitude environment simulation test cabin was developed to accurately control temperatures and pressures encountered at high altitudes. The system was developed to provide slope-tracking dynamic control of the temperature–pressure two-parameter and overcome the control difficulties inherent to a large inertia lag link with a complex control system which is composed of turbine refrigeration device, vacuum device and liquid nitrogen cooling device. The system includes multi-parameter decoupling of the cabin itself to avoid equipment damage of air refrigeration turbine caused by improper operation. Based on analysis of the dynamic characteristics and modeling for variations in temperature, pressure and rotation speed, an intelligent controller was implemented that includes decoupling and fuzzy arithmetic combined with an expert PID controller to control test parameters by decoupling and slope tracking control strategy. The control system employed centralized management in an open industrial ethernet architecture with an industrial computer at the core. The simulation and field debugging and running results show that this method can solve the problems of a poor anti-interference performance typical for a conventional PID and overshooting that can readily damage equipment. The steady-state characteristics meet the system requirements.

Effects of Cabin Upsets on Adsorption Columns for Air Revitalization

Science.gov (United States)

LeVan, Douglas

1999-01-01

The National Aeronautics and Space Administration (NASA) utilizes adsorption technology as part of contaminant removal systems designed for long term missions. A variety of trace contaminants can be effectively removed from gas streams by adsorption onto activated carbon. An activated carbon adsorption column meets NASA's requirements of a lightweight and efficient means of controlling trace contaminant levels aboard spacecraft and space stations. The activated carbon bed is part of the Trace Contaminant Control System (TCCS) which is utilized to purify the cabin atmosphere. TCCS designs oversize the adsorption columns to account for irregular fluctuations in cabin atmospheric conditions. Variations in the cabin atmosphere include changes in contaminant concentrations, temperature, and relative humidity. Excessively large deviations from typical conditions can result from unusual crew activity, equipment malfunctions, or even fires. The research carried out under this award focussed in detail on the effects of cabin upsets on the performance of activated carbon adsorption columns. Both experiments and modeling were performed with an emphasis on the roll of a change in relative humidity on adsorption of trace contaminants. A flow through fixed-bed apparatus was constructed at the NASA Ames Research Center, and experiments were performed there. Modeling work was performed at the University of Virginia.

Cabin crew collectivism: labour process and the roots of mobilization

OpenAIRE

Taylor, P.; Moore, S.

2015-01-01

The protracted dispute (2009–11) between British Airways and BASSA (British Airways Stewards and Stewardesses Association) was notable for the strength of collective action by cabin crew. In-depth interviews reveal collectivism rooted in the labour process and highlight the key agency of BASSA in effectively articulating worker interests. This data emphasizes crews’ relative autonomy, sustained by unionate on-board Cabin Service Directors who have defended the frontier of control against mana...

A new calcineurin inhibition domain in Cabin1

International Nuclear Information System (INIS)

Jang, Hyonchol; Cho, Eun-Jung; Youn, Hong-Duk

2007-01-01

Calcineurin (CN), a calcium-activated phosphatase, plays a critical role in various biological processes including T cell activation. Cabin1, a calcineurin binding protein 1, has been shown to bind directly to CN using its C-terminal region and inhibit CN activity. However, no increase in CN activity has been found in Cabin1ΔC T cells, which produce a truncated Cabin1 lacking the C-terminal CN binding region. Here, we report that Cabin1 has additional CN binding domain in its 701-900 amino acid residues. Cabin1 (701-900) blocked both CN-mediated dephosphorylation and nuclear import of NFAT and thus inhibited IL-2 production in response to PMA/ionomycin stimulation. This fact may explain why Cabin1ΔC mice previously showed no significant defect in CN-mediated signaling pathway

Cancer incidence among Nordic airline cabin crew.

Science.gov (United States)

Pukkala, Eero; Helminen, Mika; Haldorsen, Tor; Hammar, Niklas; Kojo, Katja; Linnersjö, Anette; Rafnsson, Vilhjálmur; Tulinius, Hrafn; Tveten, Ulf; Auvinen, Anssi

2012-12-15

Airline cabin crew are occupationally exposed to cosmic radiation and jet lag with potential disruption of circadian rhythms. This study assesses the influence of work-related factors in cancer incidence of cabin crew members. A cohort of 8,507 female and 1,559 male airline cabin attendants from Finland, Iceland, Norway and Sweden was followed for cancer incidence for a mean follow-up time of 23.6 years through the national cancer registries. Standardized incidence ratios (SIRs) were defined as ratios of observed and expected numbers of cases. A case-control study nested in the cohort (excluding Norway) was conducted to assess the relation between the estimated cumulative cosmic radiation dose and cumulative number of flights crossing six time zones (indicator of circadian disruption) and cancer risk. Analysis of breast cancer was adjusted for parity and age at first live birth. Among female cabin crew, a significantly increased incidence was observed for breast cancer [SIR 1.50, 95% confidence interval (95% CI) 1.32-1.69], leukemia (1.89, 95% CI 1.03-3.17) and skin melanoma (1.85, 95% CI 1.41-2.38). Among men, significant excesses in skin melanoma (3.00, 95% CI 1.78-4.74), nonmelanoma skin cancer (2.47, 95% CI 1.18-4.53), Kaposi sarcoma (86.0, 95% CI 41.2-158) and alcohol-related cancers (combined SIR 3.12, 95% CI 1.95-4.72) were found. This large study with complete follow-up and comprehensive cancer incidence data shows an increased incidence of several cancers, but according to the case-control analysis, excesses appear not to be related to the cosmic radiation or circadian disruptions from crossing multiple time zones. Copyright © 2012 UICC.

Maximum vehicle cabin temperatures under different meteorological conditions

Science.gov (United States)

Grundstein, Andrew; Meentemeyer, Vernon; Dowd, John

2009-05-01

A variety of studies have documented the dangerously high temperatures that may occur within the passenger compartment (cabin) of cars under clear sky conditions, even at relatively low ambient air temperatures. Our study, however, is the first to examine cabin temperatures under variable weather conditions. It uses a unique maximum vehicle cabin temperature dataset in conjunction with directly comparable ambient air temperature, solar radiation, and cloud cover data collected from April through August 2007 in Athens, GA. Maximum cabin temperatures, ranging from 41-76°C, varied considerably depending on the weather conditions and the time of year. Clear days had the highest cabin temperatures, with average values of 68°C in the summer and 61°C in the spring. Cloudy days in both the spring and summer were on average approximately 10°C cooler. Our findings indicate that even on cloudy days with lower ambient air temperatures, vehicle cabin temperatures may reach deadly levels. Additionally, two predictive models of maximum daily vehicle cabin temperatures were developed using commonly available meteorological data. One model uses maximum ambient air temperature and average daily solar radiation while the other uses cloud cover percentage as a surrogate for solar radiation. From these models, two maximum vehicle cabin temperature indices were developed to assess the level of danger. The models and indices may be useful for forecasting hazardous conditions, promoting public awareness, and to estimate past cabin temperatures for use in forensic analyses.

Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

Science.gov (United States)

DeSimpelaere, Edward

2011-01-01

The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

Design and Testing of a Thermal Storage System for Electric Vehicle Cabin Heating

Energy Technology Data Exchange (ETDEWEB)

Wang, Mingyu [MAHLE Behr Troy Inc.; WolfeIV, Edward [MAHLE Behr Troy Inc.; Craig, Timothy [MAHLE Behr Troy Inc.; LaClair, Tim J [ORNL; Gao, Zhiming [ORNL; Abdelaziz, Omar [ORNL

2016-01-01

Without the waste heat available from the engine of a conventional automobile, electric vehicles (EVs) must provide heat to the cabin for climate control using energy stored in the vehicle. In current EV designs, this energy is typically provided by the traction battery. In very cold climatic conditions, the power required to heat the EV cabin can be of a similar magnitude to that required for propulsion of the vehicle. As a result, the driving range of an EV can be reduced very significantly during winter months, which limits consumer acceptance of EVs and results in increased battery costs to achieve a minimum range while ensuring comfort to the EV driver. To minimize the range penalty associated with EV cabin heating, a novel climate control system that includes thermal energy storage has been designed for use in EVs and plug-in hybrid electric vehicles (PHEVs). The system uses the stored latent heat of an advanced phase change material (PCM) to provide cabin heating. The PCM is melted while the EV is connected to the electric grid for charging of the electric battery, and the stored energy is subsequently transferred to the cabin during driving. To minimize thermal losses when the EV is parked for extended periods, the PCM is encased in a high performance insulation system. The electrical PCM-Assisted Thermal Heating System (ePATHS) was designed to provide enough thermal energy to heat the EV s cabin for approximately 46 minutes, covering the entire daily commute of a typical driver in the U.S.

Active noise control primer

CERN Document Server

Snyder, Scott D

2000-01-01

Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...

Crane cabins' interior space multivariate anthropometric modeling.

Science.gov (United States)

Essdai, Ahmed; Spasojević Brkić, Vesna K; Golubović, Tamara; Brkić, Aleksandar; Popović, Vladimir

2018-01-01

Previous research has shown that today's crane cabins fail to meet the needs of a large proportion of operators. Performance and financial losses and effects on safety should not be overlooked as well. The first aim of this survey is to model the crane cabin interior space using up-to-date crane operator anthropometric data and to compare the multivariate and univariate method anthropometric models. The second aim of the paper is to define the crane cabin interior space dimensions that enable anthropometric convenience. To facilitate the cabin design, the anthropometric dimensions of 64 crane operators in the first sample and 19 more in the second sample were collected in Serbia. The multivariate anthropometric models, spanning 95% of the population on the basis of a set of 8 anthropometric dimensions, have been developed. The percentile method was also used on the same set of data. The dimensions of the interior space, necessary for the accommodation of the crane operator, are 1174×1080×1865 mm. The percentiles results for the 5th and 95th model are within the obtained dimensions. The results of this study may prove useful to crane cabin designers in eliminating anthropometric inconsistencies and improving the health of operators, but can also aid in improving the safety, performance and financial results of the companies where crane cabins operate.

Using the effect of alcohol as a comparison to illustrate the detrimental effects of noise on performance

Directory of Open Access Journals (Sweden)

Brett R.C Molesworth

2013-01-01

Full Text Available The aim of the present research is to provide a user-friendly index of the relative impairment associated with noise in the aircraft cabin. As such, the relative effect of noise, at a level typical of an aircraft cabin was compared with varying levels of alcohol intoxication in the same subjects. Since the detrimental effect of noise is more pronounced on non-native speakers, both native English and non-native English speakers featured in the study. Noise cancelling headphones were also tested as a simple countermeasure to mitigate the effect of noise on performance. A total of 32 participants, half of which were non-native English speakers, completed a cued recall task in two alcohol conditions (blood alcohol concentration 0.05 and 0.10 and two audio conditions (audio played through the speaker and noise cancelling headphones. The results revealed that aircraft noise at 65 dB (A negatively affected performance to a level comparable to alcohol intoxication of 0.10. The results also supported previous research that reflects positively on the benefits of noise cancelling headphones in reducing the effects of noise on performance especially for non-native English speakers. These findings provide for personnel involved in the aviation industry, a user-friendly index of the relative impairment associated with noise in the aircraft cabin as compared with the effects of alcohol. They also highlight the benefits of a simple countermeasure such as noise cancelling headphones in mitigating some of the detrimental effects of noise on performance.

Interior Noise Predictions in the Preliminary Design of the Large Civil Tiltrotor (LCTR2)

Science.gov (United States)

Grosveld, Ferdinand W.; Cabell, Randolph H.; Boyd, David D.

2013-01-01

A prediction scheme was established to compute sound pressure levels in the interior of a simplified cabin model of the second generation Large Civil Tiltrotor (LCTR2) during cruise conditions, while being excited by turbulent boundary layer flow over the fuselage, or by tiltrotor blade loading and thickness noise. Finite element models of the cabin structure, interior acoustic space, and acoustically absorbent (poro-elastic) materials in the fuselage were generated and combined into a coupled structural-acoustic model. Fluctuating power spectral densities were computed according to the Efimtsov turbulent boundary layer excitation model. Noise associated with the tiltrotor blades was predicted in the time domain as fluctuating surface pressures and converted to power spectral densities at the fuselage skin finite element nodes. A hybrid finite element (FE) approach was used to compute the low frequency acoustic cabin response over the frequency range 6-141 Hz with a 1 Hz bandwidth, and the Statistical Energy Analysis (SEA) approach was used to predict the interior noise for the 125-8000 Hz one-third octave bands.

Adjusting phenotypes by noise control.

Directory of Open Access Journals (Sweden)

Kyung H Kim

2012-01-01

Full Text Available Genetically identical cells can show phenotypic variability. This is often caused by stochastic events that originate from randomness in biochemical processes involving in gene expression and other extrinsic cellular processes. From an engineering perspective, there have been efforts focused on theory and experiments to control noise levels by perturbing and replacing gene network components. However, systematic methods for noise control are lacking mainly due to the intractable mathematical structure of noise propagation through reaction networks. Here, we provide a numerical analysis method by quantifying the parametric sensitivity of noise characteristics at the level of the linear noise approximation. Our analysis is readily applicable to various types of noise control and to different types of system; for example, we can orthogonally control the mean and noise levels and can control system dynamics such as noisy oscillations. As an illustration we applied our method to HIV and yeast gene expression systems and metabolic networks. The oscillatory signal control was applied to p53 oscillations from DNA damage. Furthermore, we showed that the efficiency of orthogonal control can be enhanced by applying extrinsic noise and feedback. Our noise control analysis can be applied to any stochastic model belonging to continuous time Markovian systems such as biological and chemical reaction systems, and even computer and social networks. We anticipate the proposed analysis to be a useful tool for designing and controlling synthetic gene networks.

Thermal comfort assessment in civil aircraft cabins

Directory of Open Access Journals (Sweden)

Pang Liping

2014-04-01

Full Text Available Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment control system (ECS that satisfies the thermal comfort for most passengers due to a number of causes. This paper adopts a corrected predicted mean vote (PMV model and an adaptive model to assess the thermal comfort conditions for 31 investigated flights and draws the conclusion that there does exist an uncomfortable thermal phenomenon in civil aircraft cabins, especially in some short-haul continental flights. It is necessary to develop an easy way to predict the thermal sensation of passengers and to direct the crew to control ECS. Due to the assessment consistency of the corrected PMV model and the adaptive model, the adaptive model of thermal neutrality temperature can be used as a method to predict the cabin optimal operative temperature. Because only the mean outdoor effective temperature ET∗ of a departure city is an input variable for the adaptive model, this method can be easily understood and implemented by the crew and can satisfy 80–90% of the thermal acceptability levels of passengers.

Large Civil Tiltrotor (LCTR2) Interior Noise Predictions due to Turbulent Boundary Layer Excitation

Science.gov (United States)

Grosveld, Ferdinand W.

2013-01-01

The Large Civil Tiltrotor (LCTR2) is a conceptual vehicle that has a design goal to transport 90 passengers over a distance of 1800 km at a speed of 556 km/hr. In this study noise predictions were made in the notional LCTR2 cabin due to Cockburn/Robertson and Efimtsov turbulent boundary layer (TBL) excitation models. A narrowband hybrid Finite Element (FE) analysis was performed for the low frequencies (6-141 Hz) and a Statistical Energy Analysis (SEA) was conducted for the high frequency one-third octave bands (125- 8000 Hz). It is shown that the interior sound pressure level distribution in the low frequencies is governed by interactions between individual structural and acoustic modes. The spatially averaged predicted interior sound pressure levels for the low frequency hybrid FE and the high frequency SEA analyses, due to the Efimtsov turbulent boundary layer excitation, were within 1 dB in the common 125 Hz one-third octave band. The averaged interior noise levels for the LCTR2 cabin were predicted lower than the levels in a comparable Bombardier Q400 aircraft cabin during cruise flight due to the higher cruise altitude and lower Mach number of the LCTR2. LCTR2 cabin noise due to TBL excitation during cruise flight was found not unacceptable for crew or passengers when predictions were compared to an acoustic survey on a Q400 aircraft.

Handbook for industrial noise control

Science.gov (United States)

The basic principles of sound, measuring techniques, and instrumentation associated with general purpose noise control are discussed. Means for identifying and characterizing a noise problem so that subsequent work may provide the most efficient and cost effective solution are outlined. A methodology for choosing appropriate noise control materials and the proper implementation of control procedures is detailed. The most significant NASA sponsored contributions to the state of the art development of optimum noise control technologies are described including cases in which aeroacoustics and related research have shed some light on ways of reducing noise generation at its source.

Design for thermal sensation and comfort states in vehicles cabins

International Nuclear Information System (INIS)

Alahmer, Ali; Abdelhamid, Mahmoud; Omar, Mohammed

2012-01-01

This manuscript investigates the analysis and modeling of vehicular thermal comfort parameters using a set of designed experiments aided by thermography measurements. The experiments are conducted using a full size climatic chamber to host the test vehicle, to accurately assess the transient and steady state temperature distributions of the test vehicle cabin. Further investigate the thermal sensation (overall and local) and the human comfort states under artificially created relative humidity scenarios. The thermal images are calibrated through a thermocouples network, while the outside temperature and relative humidity are manipulated through the climatic environmental chamber with controlled soaking periods to guarantee the steady state conditions for each test scenario. The relative humidity inside the passenger cabin is controlled using a Total Humidity Controller (THC). The simulation uses the experimentally extracted boundary conditions via a 3-D Berkeley model that is set to be fully transient to account for the interactions in the velocity and temperature fields in the passenger compartment, which included interactions from turbulent flow, thermal buoyancy and the three modes of heat transfer conduction, convection and radiation. The model investigates the human comfort by analyzing the effect of the in-cabin relative humidity from two specific perspectives; firstly its effect on the body temporal variation of temperature within the cabin. Secondly, the Local Sensation (LS) and Comfort (LC) are analyzed for the different body segments in addition to the Overall Sensation (OS) and the Overall Comfort (OC). Furthermore, the human sensation is computed using the Fanger model in terms of the Predicted Mean Value (PMV) and the Predicted Percentage Dissatisfied (PPD) indices. The experimental and simulation results show that controlling the RH levels during the heating and the cooling processes (winter and summer conditions respectively) aid the A/C system to

Research on release rate of volatile organic compounds in typical vessel cabin

Directory of Open Access Journals (Sweden)

ZHANG Jinlan

2018-02-01

Full Text Available [Objectives] Volatile Organic Compounds (VOC should be efficiently controlled in vessel cabins to ensure the crew's health and navigation safety. As an important parameter, research on release rate of VOCs in cabins is required. [Methods] This paper develops a method to investigate this parameter of a ship's cabin based on methods used in other closed indoor environments. A typical vessel cabin is sampled with Tenax TA tubes and analyzed by Automated Thermal Desorption-Gas Chromatography-Mass Spectrometry (ATD-GC/MS. The lumped mode is used and the release rate of Benzene, Toluene, Ethylbenzene and Xylene (BTEX, the typical representatives of VOCs, is obtained both in closed and ventilated conditions. [Results] The results show that the content of xylene and Total Volatile Organic Compounds (TVOC exceed the indoor environment standards in ventilated conditions. The BTEX release rate is similar in both conditions except for the benzene. [Conclusions] This research builds a method to measure the release rate of VOCs, providing references for pollution character evaluation and ventilation and purification system design.

Development of Active Noise Control System for Quieting Transformer Noise

Energy Technology Data Exchange (ETDEWEB)

Lee, Bok Kyu; Song, Seik Young; Choi, Huo Yul [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Yun, Dae Hea; Lee, Hyuk Jae [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

1997-12-31

The passive noise control technique made use of sound-absorbing or soundproofing materials, so it required a large area and high cost for installation and had a drawback of poor performance at low frequency. Compared to this, the Active Noise Control attenuates noise sound pressure by using secondary source which has same performance ay low-frequency. Furthermore, it is able to save space and expenses. - research on adaptive algorithms - evaluation of global attenuation of the control - computer simulation - real-time Active Noise Control System Hardware Implementation - ANC system setting in the noisy area.

Active control of the noise

International Nuclear Information System (INIS)

Rodriguez V, Luis Alfonso; Lopez Q, Jose German

2001-01-01

The problems of acoustic noise are more and more preponderant in the measure in that the amount of equipment and industrial machinery is increased such as fans, transformers, compressors etc. the use of devices passive mechanics for the reduction of the noise is effective and very appreciated because its effects embrace a wide range of acoustic frequency. However, to low frequencies, such devices become too big and expensive besides that present a tendency to do not effective. The control of active noise, CAN, using the electronic generation anti-noise, constitutes an interesting solution to the problem because their operation principle allows achieving an appreciable reduction of the noise by means of the use of compact devices. The traditional techniques for the control of acoustic noise like barriers and silenced to attenuate it, are classified as passive and their works has been accepted as norm as for the treatment of problems of noise it refers. Such techniques are considered in general very effective in the attenuation of noise of wide band. However, for low frequency, the required passive structures are too big and expensive; also, their effectiveness diminishes flagrantly, that which makes them impractical in many applications. The active suppression is profiled like a practical alternative for the reduction of acoustic noise. The idea in the active treatment of the noise it contemplates the use of a device electro-acoustic, like a speaker for example that it cancels to the noise by the generation of sounds of Same width and of contrary phase (anti-noise). The cancellation phenomenon is carried out when the ant-noise combines acoustically with the noise, what is in the cancellation of both sounds. The effectiveness of the cancellation of the primary source of noise depends on the precision with which the width and the phase of the generated ant-noise are controlled. The active control of noise, ANC (activates noise control), it is being investigated for

Control of interior surface materials for speech privacy in high-speed train cabins.

Science.gov (United States)

Jang, H S; Lim, H; Jeon, J Y

2017-05-01

The effect of interior materials with various absorption coefficients on speech privacy was investigated in a 1:10 scale model of one high-speed train cabin geometry. The speech transmission index (STI) and privacy distance (r P ) were measured in the train cabin to quantify speech privacy. Measurement cases were selected for the ceiling, sidewall, and front and back walls and were classified as high-, medium- and low-absorption coefficient cases. Interior materials with high absorption coefficients yielded a low r P , and the ceiling had the largest impact on both the STI and r P among the interior elements. Combinations of the three cases were measured, and the maximum reduction in r P by the absorptive surfaces was 2.4 m, which exceeds the space between two rows of chairs in the high-speed train. Additionally, the contribution of the interior elements to speech privacy was analyzed using recorded impulse responses and a multiple regression model for r P using the equivalent absorption area. The analysis confirmed that the ceiling was the most important interior element for improving speech privacy. These results can be used to find the relative decrease in r P in the acoustic design of interior materials to improve speech privacy in train cabins. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Modeling the Fate of Expiratory Aerosols and the Associated Infection Risk in an Aircraft Cabin Environment

DEFF Research Database (Denmark)

Wan, M.P.; To, G.N.S.; Chao, C.Y.H.

2009-01-01

to estimate the risk of infection by contact. The environmental control system (ECS) in a cabin creates air circulation mainly in the lateral direction, making lateral dispersions of aerosols much faster than longitudinal dispersions. Aerosols with initial sizes under 28 m in diameter can stay airborne......The transport and deposition of polydispersed expiratory aerosols in an aircraft cabin were simulated using a Lagrangian-based model validated by experiments conducted in an aircraft cabin mockup. Infection risk by inhalation was estimated using the aerosol dispersion data and a model was developed...

Irregular working hours and fatigue of cabin crew.

Science.gov (United States)

Castro, Marta; Carvalhais, José; Teles, Júlia

2015-01-01

Beyond workload and specific environmental factors, flight attendants can be exposed to irregular working hours, conflicting with their circadian rhythms and having a negative impact in sleep, fatigue, health, social and family life, and performance which is critical to both safety and security in flight operations. This study focuses on the irregular schedules of cabin crew as a trigger of fatigue symptoms in a wet lease Portuguese airline. The aim was to analyze: what are the requirements of the cabin crew work; whether the schedules being observed and effective resting timeouts are triggering factors of fatigue; and the existence of fatigue symptoms in the cabin crew. A questionnaire has been adapted and applied to a sample of 73 cabin crew-members (representing 61.9% of the population), 39 females and 34 males, with an average age of 27.68 ± 4.27 years. Our data indicate the presence of fatigue and corresponding health symptoms among the airline cabin crew, despite of the sample favorable characteristics. Senior workers and women are more affected. Countermeasures are required. Recommendations can be made regarding the fatigue risk management, including work organization, education and awareness training programmes and specific countermeasures.

Experimental investigation of thermal comfort and air quality in an automobile cabin during the cooling period

Energy Technology Data Exchange (ETDEWEB)

Kilic, M.; Akyol, S.M. [Uludag University, Department of Mechanical Engineering, Faculty of Engineering and Architecture, Bursa (Turkey)

2012-08-15

The air quality and thermal comfort strongly influenced by the heat and mass transfer take place together in an automobile cabin. In this study, it is aimed to investigate and assess the effects of air intake settings (recirculation and fresh air) on the thermal comfort, air quality satisfaction and energy usage during the cooling period of an automobile cabin. For this purpose, measurements (temperature, air velocity, CO{sub 2}) were performed at various locations inside the cabin. Furthermore, whole body and local responses of the human subjects were noted while skin temperatures were measured. A mathematical model was arranged in order to estimate CO{sub 2} concentration and energy usage inside the vehicle cabin and verified with experimental data. It is shown that CO{sub 2} level inside of the cabin can be greater than the threshold value recommended for the driving safety if two and more occupants exist in the car. It is also shown that an advanced climate control system may satisfy the requirements for the air quality and thermal comfort as well as to reduce the energy usage for the cooling of a vehicle cabin. (orig.)

Experimental investigation of thermal comfort and air quality in an automobile cabin during the cooling period

Science.gov (United States)

Kilic, M.; Akyol, S. M.

2012-08-01

The air quality and thermal comfort strongly influenced by the heat and mass transfer take place together in an automobile cabin. In this study, it is aimed to investigate and assess the effects of air intake settings (recirculation and fresh air) on the thermal comfort, air quality satisfaction and energy usage during the cooling period of an automobile cabin. For this purpose, measurements (temperature, air velocity, CO2) were performed at various locations inside the cabin. Furthermore, whole body and local responses of the human subjects were noted while skin temperatures were measured. A mathematical model was arranged in order to estimate CO2 concentration and energy usage inside the vehicle cabin and verified with experimental data. It is shown that CO2 level inside of the cabin can be greater than the threshold value recommended for the driving safety if two and more occupants exist in the car. It is also shown that an advanced climate control system may satisfy the requirements for the air quality and thermal comfort as well as to reduce the energy usage for the cooling of a vehicle cabin.

A Cabin Air Separator for EVA Oxygen

Science.gov (United States)

Graf, John C.

2011-01-01

Presently, the Extra-Vehicular Activities (EVAs) conducted from the Quest Joint Airlock on the International Space Station use high pressure, high purity oxygen that is delivered to the Space Station by the Space Shuttle. When the Space Shuttle retires, a new method of delivering high pressure, high purity oxygen to the High Pressure Gas Tanks (HPGTs) is needed. One method is to use a cabin air separator to sweep oxygen from the cabin air, generate a low pressure/high purity oxygen stream, and compress the oxygen with a multistage mechanical compressor. A main advantage to this type of system is that the existing low pressure oxygen supply infrastructure can be used as the source of cabin oxygen. ISS has two water electrolysis systems that deliver low pressure oxygen to the cabin, as well as chlorate candles and compressed gas tanks on cargo vehicles. Each of these systems can feed low pressure oxygen into the cabin, and any low pressure oxygen source can be used as an on-board source of oxygen. Three different oxygen separator systems were evaluated, and a two stage Pressure Swing Adsorption system was selected for reasons of technical maturity. Two different compressor designs were subjected to long term testing, and the compressor with better life performance and more favorable oxygen safety characteristics was selected. These technologies have been used as the basis of a design for a flight system located in Equipment Lock, and taken to Preliminary Design Review level of maturity. This paper describes the Cabin Air Separator for EVA Oxygen (CASEO) concept, describes the separator and compressor technology trades, highlights key technology risks, and describes the flight hardware concept as presented at Preliminary Design Review (PDR)

Simulations of heat transfer through the cabin walls of rail vehicle

Directory of Open Access Journals (Sweden)

Schuster M.

2007-10-01

Full Text Available This paper deals with industrial application of numerical methods to the prediction of thermal situation in the rail vehicle interior. Basic principles of heat transfer are summarised to explain both theoretical background of simulations and engineering approach to solving temperature conditions in the vehicle interior. The main part of the contribution describes the solution of the locomotive driver’s cabin heating and controlling the temperature levels. This contribution is a brief overview of both possibilities of engineering modelling of heat transfer modes and results in the simulation of the real locomotive cabin heating/ventilation system design.

Occupational cosmic radiation exposure and cancer in airline cabin crew

International Nuclear Information System (INIS)

Kojo, K.

2013-03-01

Cosmic radiation dose rates are considerably higher at cruising altitudes of airplanes than at ground level. Previous studies have found increased risk of certain cancers among aircraft cabin crew, but the results are not consistent across different studies. Despite individual cosmic radiation exposure assessment is important for evaluating the relation between cosmic radiation exposure and cancer risk, only few previous studies have tried to develop an exposure assessment method. The evidence for adverse health effects in aircrews due to ionizing radiation is inconclusive because quantitative dose estimates have not been used. No information on possible confounders has been collected. For an occupational group with an increased risk of certain cancers it is very important to assess if the risk is related to occupational exposure. The goal of this thesis was to develop two separate retrospective exposure assessment methods for occupational exposure to cosmic radiation. The methods included the assessment based on survey on flight histories and based on company flight timetables. Another goal was to describe the cancer incidence among aircraft cabin crew with a large cohort in four Nordic countries, i.e., Finland, Iceland, Norway, and Sweden. Also the contribution of occupational as well as non-occupational factors to breast and skin cancer risk among the cabin crew was studied with case-control studies. Using the survey method of cosmic radiation exposure assessment, the median annual radiation dose of Finnish airline cabin crew was 0.6 milliSievert (mSv) in the 1960s, 3.3 mSv in the 1970s, and 3.6 mSv in the 1980s. With the flight timetable method, the annual radiation dose increased with time being 0.7 mSv in the 1960 and 2.1 mSv in the 1995. With the survey method, the median career dose was 27.9 mSv and with the timetable method 20.8 mSv. These methods provide improved means for individual cosmic radiation exposure assessment compared to studies where cruder

Occupational cosmic radiation exposure and cancer in airline cabin crew.

Energy Technology Data Exchange (ETDEWEB)

Kojo, K.

2013-03-15

Cosmic radiation dose rates are considerably higher at cruising altitudes of airplanes than at ground level. Previous studies have found increased risk of certain cancers among aircraft cabin crew, but the results are not consistent across different studies. Despite individual cosmic radiation exposure assessment is important for evaluating the relation between cosmic radiation exposure and cancer risk, only few previous studies have tried to develop an exposure assessment method. The evidence for adverse health effects in aircrews due to ionizing radiation is inconclusive because quantitative dose estimates have not been used. No information on possible confounders has been collected. For an occupational group with an increased risk of certain cancers it is very important to assess if the risk is related to occupational exposure. The goal of this thesis was to develop two separate retrospective exposure assessment methods for occupational exposure to cosmic radiation. The methods included the assessment based on survey on flight histories and based on company flight timetables. Another goal was to describe the cancer incidence among aircraft cabin crew with a large cohort in four Nordic countries, i.e., Finland, Iceland, Norway, and Sweden. Also the contribution of occupational as well as non-occupational factors to breast and skin cancer risk among the cabin crew was studied with case-control studies. Using the survey method of cosmic radiation exposure assessment, the median annual radiation dose of Finnish airline cabin crew was 0.6 milliSievert (mSv) in the 1960s, 3.3 mSv in the 1970s, and 3.6 mSv in the 1980s. With the flight timetable method, the annual radiation dose increased with time being 0.7 mSv in the 1960 and 2.1 mSv in the 1995. With the survey method, the median career dose was 27.9 mSv and with the timetable method 20.8 mSv. These methods provide improved means for individual cosmic radiation exposure assessment compared to studies where cruder

Active noise control in a duct to cancel broadband noise

Science.gov (United States)

Chen, Kuan-Chun; Chang, Cheng-Yuan; Kuo, Sen M.

2017-09-01

The paper presents cancelling duct noises by using the active noise control (ANC) techniques. We use the single channel feed forward algorithm with feedback neutralization to realize ANC. Several kinds of ducts noises including tonal noises, sweep tonal signals, and white noise had investigated. Experimental results show that the proposed ANC system can cancel these noises in a PVC duct very well. The noise reduction of white noise can be up to 20 dB.

An Exploratory Analysis of Sound Field Characteristics using the Impulse Response in a Car Cabin

Directory of Open Access Journals (Sweden)

Yoshiharu Soeta

2018-03-01

Full Text Available Sound environments in cars are becoming quieter and receiving attention because of the prevalence of low-noise engines such as hybrid and electric engines and the manifestation of automated driving. Although the car cabin has potential as a listening space, its acoustic quality has not been examined in detail. The present study investigated sound field characteristics in the car cabin using acoustic parameters obtained by impulse response analysis. In particular, effects of the passenger position, open windows and the use of an air conditioner on acoustic parameters were investigated. The passenger position affected the sound strength at low frequencies. Rear seats, except for the rear central seat, had lower interaural correlation than the front seats, suggesting that rear seats have more diffused sound fields. The opening of windows and use of air conditioners attenuated the ratio of early- and late-arriving energy at high frequencies, suggesting a loss of clarity for music.

Aircraft Cabin Environmental Quality Sensors

Energy Technology Data Exchange (ETDEWEB)

Gundel, Lara; Kirchstetter, Thomas; Spears, Michael; Sullivan, Douglas

2010-05-06

The Indoor Environment Department at Lawrence Berkeley National Laboratory (LBNL) teamed with seven universities to participate in a Federal Aviation Administration (FAA) Center of Excellence (COE) for research on environmental quality in aircraft. This report describes research performed at LBNL on selecting and evaluating sensors for monitoring environmental quality in aircraft cabins, as part of Project 7 of the FAA's COE for Airliner Cabin Environmental Research (ACER)1 effort. This part of Project 7 links to the ozone, pesticide, and incident projects for data collection and monitoring and is a component of a broader research effort on sensors by ACER. Results from UCB and LBNL's concurrent research on ozone (ACER Project 1) are found in Weschler et al., 2007; Bhangar et al. 2008; Coleman et al., 2008 and Strom-Tejsen et al., 2008. LBNL's research on pesticides (ACER Project 2) in airliner cabins is described in Maddalena and McKone (2008). This report focused on the sensors needed for normal contaminants and conditions in aircraft. The results are intended to complement and coordinate with results from other ACER members who concentrated primarily on (a) sensors for chemical and biological pollutants that might be released intentionally in aircraft; (b) integration of sensor systems; and (c) optimal location of sensors within aircraft. The parameters and sensors were selected primarily to satisfy routine monitoring needs for contaminants and conditions that commonly occur in aircraft. However, such sensor systems can also be incorporated into research programs on environmental quality in aircraft cabins.

Redesign of Transjakarta Bus Driver's Cabin

Science.gov (United States)

Mardi Safitri, Dian; Azmi, Nora; Singh, Gurbinder; Astuti, Pudji

2016-02-01

Ergonomic risk at work stations with type Seated Work Control was one of the problems faced by Transjakarta bus driver. Currently “Trisakti” type bus, one type of bus that is used by Transjakarta in corridor 9, serving route Pinang Ranti - Pluit, gained many complaints from drivers. From the results of Nordic Body Map questionnaires given to 30 drivers, it was known that drivers feel pain in the neck, arms, hips, and buttocks. Allegedly this was due to the seat position and the button/panel bus has a considerable distance range (1 meter) to be achieved by drivers. In addition, preliminary results of the questionnaire using Workstation Checklist identified their complaints about uncomfortable cushion, driver's seat backrest, and the exact position of the AC is above the driver head. To reduce the risk level of ergonomics, then did research to design the cabin by using a generic approach to designing products. The risk analysis driver posture before the design was done by using Rapid Upper Limb Assessment (RULA), Rapid Entire Body Assessment (REBA), and Quick Exposure Checklist (QEC), while the calculation of the moment the body is done by using software Mannequin Pro V10.2. Furthermore, the design of generic products was done through the stages: need metric-matrix, house of quality, anthropometric data collection, classification tree concept, concept screening, scoring concept, design and manufacture of products in the form of two-dimensional. While the design after design risk analysis driver posture was done by using RULA, REBA, and calculation of moments body as well as the design visualized using software 3DMax. From the results of analysis before the draft design improvements cabin RULA obtained scores of 6, REBA 9, and the result amounted to 57.38% QEC and moment forces on the back is 247.3 LbF.inch and on the right hip is 72.9 LbF.in. While the results of the proposed improvements cabin design RULA obtained scores of 3, REBA 4, and the moment of force on

14 CFR 23.571 - Metallic pressurized cabin structures.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Metallic pressurized cabin structures. 23... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.571 Metallic pressurized cabin structures. For normal, utility, and acrobatic...

Ship cabin leakage alarm based on ARM SCM

Science.gov (United States)

Qu, Liyan

2018-03-01

If there is a leakage in the cabin of a sailing ship, it is a major accident that threatens the personnel and property of the ship. If we can’t take timely measures, there will be a devastating disaster. In order to judge the leakage of the cabin, it is necessary to set up a leakage alarm system, so as to achieve the purpose of detecting and alarming the leakage of the cabin, and avoid the occurrence of accidents. This paper discusses the design of ship cabin leakage alarm system based on ARM SCM. In order to ensure the stability and precision of the product, the hardware design of the alarm system is carried out, such as circuit design, software design, the programming of SCM, the software programming of upper computer, etc. It is hoped that it can be of reference value to interested readers.

Human Factors in Cabin Accident Investigations

Science.gov (United States)

Chute, Rebecca D.; Rosekind, Mark R. (Technical Monitor)

1996-01-01

Human factors has become an integral part of the accident investigation protocol. However, much of the investigative process remains focussed on the flight deck, airframe, and power plant systems. As a consequence, little data has been collected regarding the human factors issues within and involving the cabin during an accident. Therefore, the possibility exists that contributing factors that lie within that domain may be overlooked. The FAA Office of Accident Investigation is sponsoring a two-day workshop on cabin safety accident investigation. This course, within the workshop, will be of two hours duration and will explore relevant areas of human factors research. Specifically, the three areas of discussion are: Information transfer and resource management, fatigue and other physical stressors, and the human/machine interface. Integration of these areas will be accomplished by providing a suggested checklist of specific cabin-related human factors questions for investigators to probe following an accident.

Cabin Environment Physics Risk Model

Science.gov (United States)

Mattenberger, Christopher J.; Mathias, Donovan Leigh

2014-01-01

This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.

Interference elimination: nuclear spin in the cabin

International Nuclear Information System (INIS)

Anon.

1984-01-01

Constructed on Michael Faraday's cage principle, such cabins enable nuclear spin tomographs to operate undisturbed by foreign radiation. The working signals of these medical research apparatus are screened from the environment so that radio and television reception are not affected. Details are given of the structure of the cabin, of the prefabricated structural elements of non-magnetic materials (chromium-nickel steel). (Auth.)

Controlled Noise Seismology

KAUST Repository

Hanafy, Sherif M.

2015-08-19

We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.

Controlled Noise Seismology

KAUST Repository

Hanafy, Sherif M.; AlTheyab, Abdullah; Schuster, Gerard T.

2015-01-01

We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.

Aircraft Instrument, Fire Protection, Warning, Communication, Navigation and Cabin Atmosphere Control System (Course Outline), Aviation Mechanics 3 (Air Frame): 9067.04.

Science.gov (United States)

Dade County Public Schools, Miami, FL.

This document presents an outline for a 135-hour course designed to familiarize the student with manipulative skills and theoretical knowledge concerning aircraft instrument systems like major flight and engine instruments; fire protection and fire fighting systems; warning systems and navigation systems; aircraft cabin control systems, such as…

Influence of a controlled environment simulating an in-flight airplane cabin on dry eye disease.

Science.gov (United States)

Tesón, Marisa; González-García, María J; López-Miguel, Alberto; Enríquez-de-Salamanca, Amalia; Martín-Montañez, Vicente; Benito, María Jesús; Mateo, María Eugenia; Stern, Michael E; Calonge, Margarita

2013-03-01

To evaluate symptoms, signs, and the levels of 16 tears inflammatory mediators of dry eye (DE) patients exposed to an environment simulating an in-flight air cabin in an environmental chamber. Twenty DE patients were exposed to controlled environment simulating an in-flight airplane cabin (simulated in-flight condition [SIC]) of 23°C, 5% relative humidity, localized air flow, and 750 millibars (mb) of barometric pressure. As controls, 15 DE patients were subjected to a simulated standard condition (SSC) of 23°C, 45% relative humidity, and 930 mb. A DE symptoms questionnaire, diagnostic tests, and determination of 16 tear molecules by multiplex bead array were performed before and 2 hours after exposure. After SIC exposure, DE patients became more symptomatic, suffered a significant (P ≤ 0.05) decrease in tear stability (tear break up time) (from 2.18 ± 0.28 to 1.53 ± 0.20), and tear volume (phenol red thread test), and a significant (P ≤ 0.05) increase in corneal staining, both globally (0.50 ± 0.14 before and 1.25 ± 0.19 after) and in each area (Baylor scale). After SSC, DE patients only showed a mild, but significant (P ≤ 0.05), increase in central and inferior corneal staining. Consistently, tear levels of IL-6 and matrix metalloproteinase (MMP)-9 significantly increased and tear epidermal growth factor (EGF) significantly decreased (P ≤ 0.05) only after SIC. The controlled adverse environment conditions in this environmental chamber can simulate the conditions in which DE patients might be exposed during flight. As this clearly impaired their lacrimal functional unit, it would be advisable that DE patients use therapeutic strategies capable of ameliorating these adverse episodes.

A Systematic Approach to Identify Sources of Abnormal Interior Noise for a High-Speed Train

Directory of Open Access Journals (Sweden)

Jie Zhang

2018-01-01

Full Text Available A systematic approach to identify sources of abnormal interior noise occurring in a high-speed train is presented and applied in this paper to resolve a particular noise issue. This approach is developed based on a number of previous dealings with similar noise problems. The particular noise issue occurs in a Chinese high-speed train. It is measured that there is a difference of 7 dB(A in overall Sound Pressure Level (SPL between two nominally identical VIP cabins at 250 km/h. The systematic approach is applied to identify the root cause of the 7 dB(A difference. Well planned measurements are performed in both the VIP cabins. Sound pressure contributions, either in terms of frequency band or in terms of facing area, are analyzed. Order analysis is also carried out. Based on these analyses, it is found that the problematic frequency is the sleeper passing frequency of the train, and an area on the roof contributes the most. In order to determine what causes that area to be the main contributor without disassembling the structure of the roof, measured noise and vibration data for different train speeds are further analyzed. It is then reasoned that roof is the main contributor caused by sound pressure behind the panel. Up to this point, panels of the roof are removed, revealing that a hole of 300 cm2 for running cables is presented behind the red area without proper sound insulation. This study can provide a basis for abnormal interior noise analysis and control of high-speed trains.

Assessment of the noise annoyance among subway train conductors in Tehran, Iran.

Science.gov (United States)

Hamidi, Mansoureh; Kavousi, Amir; Zaheri, Somayeh; Hamadani, Abolfazl; Mirkazemi, Roksana

2014-01-01

Subway transportation system is a new phenomenon in Iran. Noise annoyance interferes with the individual's task performance, and the required alertness in the driving of subway trains. This is the first study conducted to measure the level of noise and noise annoyance among conductors of subway organization in Tehran, Iran. This cross sectional study was conducted among 167 randomly selected train conductors. Information related to noise annoyance was collected by using a self-administered questionnaire. The dosimetry and sound metering was done for the conductors and inside the cabins. There were 41 sound metering measuring samples inside the conductors' cabin, and there were 12 samples of conductors' noise exposure. The results of sound level meter showed that the mean Leq was 73.0 dBA ± 8.7 dBA and the dosimetry mean measured Leq was 82.1 dBA ± 6.8 dBA. 80% of conductors were very annoyed/annoyed by noise in their work place. 53.9% of conductors reported that noise affected their work performance and 63.5% reported that noise causes that they lose their concentration. The noise related to movement of train wheels on rail was reported as the worst by 83.2% followed by the noise of brakes (74.3%) and the ventilation noise (71.9%). 56.9% of conductors reported that they are suffering from sleeplessness, 40.1% from tinnitus and 80.2% feeling fatigue and sleepy. The study results showed the high level of noise and noise annoyance among train conductors and the poor health outcome of their exposure to this level of noise.

Health Effects of Airline Cabin Environments in Simulated 8-Hour Flights.

Science.gov (United States)

2017-07-01

Commercial air travel is usually without health incidents. However, there is a view that cabin environments may be detrimental to health, especially flights of 8 h or more. Concerns have been raised about deep vein thrombosis, upper respiratory tract infections, altitude sickness, and toxins from the engines. Passenger cabin simulators were used to achieve a comparative observational study with 8-h flights at pressures equivalent to terrestrial altitudes of ground, 4000, 6000, and 8000 ft. Biomarkers of thrombosis (D-Dimer), inflammation (interleukin-6), and respiratory dysfunction (FEV1) and oxygen saturation (Spo2) were measured, as well as pulse and blood pressure. The wellbeing of the passengers was also monitored. During 36 flights, 1260 healthy subjects [626 women (F) and 634 men (M) (mean age = 43, SD = 16)] were assessed. Additionally, 72 subjects with chronic obstructive pulmonary disease (F = 32, M = 40, mean age = 48, SD = 17) and 74 with heart failure (F = 50, M = 24, mean age = 54, SD = 14) contributed to 11 flights. Additionally, 76 normal controls were observed while engaged in a usual day's work (F = 38, M = 38, mean age = 39, SD = 15). There were no health-significant changes in D-Dimer, interleukin-6, or FEV1. Spo2 varied as expected, with lowest values at 8000 ft and in patients with cardiopulmonary disease. The only differences from the controls were the loss of the normal diurnal variations in interleukin-6 and D-Dimer. This very large, comparative, controlled study provides much reassurance for the traveling public, who use airline flights of up to 8 h. We did not show evidence of the development of venous thrombosis, inflammation, respiratory embarrassment, nor passenger distress. No significant symptoms or adverse effects were reported.Ideal Cabin Environment (ICE) Research Consortium of the European Community 6th Framework Programme. Health effects of airline cabin environments in simulated 8-hour flights. Aerosp Med Hum Perform. 2017; 88(7):651-656.

Impacts of an Ammonia Leak on the Cabin Atmosphere of the International Space Station

Science.gov (United States)

Duchesne, Stephanie M.; Sweterlitsch, Jeffrey J.; Son, Chang H.; Perry Jay L.

2012-01-01

Toxic chemical release into the cabin atmosphere is one of the three major emergency scenarios identified on the International Space Station (ISS). The release of anhydrous ammonia, the coolant used in the U.S. On-orbit Segment (USOS) External Active Thermal Control Subsystem (EATCS), into the ISS cabin atmosphere is one of the most serious toxic chemical release cases identified on board ISS. The USOS Thermal Control System (TCS) includes an Internal Thermal Control Subsystem (ITCS) water loop and an EATCS ammonia loop that transfer heat at the interface heat exchanger (IFHX). Failure modes exist that could cause a breach within the IFHX. This breach would result in high pressure ammonia from the EATCS flowing into the lower pressure ITCS water loop. As the pressure builds in the ITCS loop, it is likely that the gas trap, which has the lowest maximum design pressure within the ITCS, would burst and cause ammonia to enter the ISS atmosphere. It is crucial to first characterize the release of ammonia into the ISS atmosphere in order to develop methods to properly mitigate the environmental risk. This paper will document the methods used to characterize an ammonia leak into the ISS cabin atmosphere. A mathematical model of the leak was first developed in order to define the flow of ammonia into the ISS cabin atmosphere based on a series of IFHX rupture cases. Computational Fluid Dynamics (CFD) methods were then used to model the dispersion of the ammonia throughout the ISS cabin and determine localized effects and ventilation effects on the dispersion of ammonia. Lastly, the capabilities of the current on-orbit systems to remove ammonia were reviewed and scrubbing rates of the ISS systems were defined based on the ammonia release models. With this full characterization of the release of ammonia from the USOS TCS, an appropriate mitigation strategy that includes crew and system emergency response procedures, personal protection equipment use, and atmosphere monitoring

Application of automation for low cost aircraft cabin simulator

NARCIS (Netherlands)

Tan, C.F.; Chen, W.; Boomen, van den G.J.A.; Rauterberg, G.W.M.

2010-01-01

This paper presents an application of automation for low cost aircraft cabin simulator. The aircraft cabin simulator is a testbed that was designed for research on aircraft passenger comfort mprovement product. The simulator consists of an economy class section, a business class section, a lavatory

Towards comfortable and efficient man-machine interaction in the cabins of vehicles

NARCIS (Netherlands)

Looze, M.P. de; Roetting, M.; Vink, P.; Luczak, H.

2000-01-01

The comfort of the operators in the cabins of vehicles is getting an increasingly important issue. At first glance, the cabins of professional machines (earth-moving equipment, busses, harvesting equipment) might look modern and highly comfortable. However, this does not imply that the cabins

A parametric study of influence of material properties on car cabin environment

Directory of Open Access Journals (Sweden)

Pokorny Jan

2014-03-01

Full Text Available Recently the author presented the paper describing a car cabin heat load model for the prediction of the car cabin environment. The model allowed to simulate a transient behavior of the car cabin, i.e. radiant temperature of surfaces, air temperature and relative humidity. The model was developed in Dymola and was built on the basic principles of thermodynamics and heat balance equations. The model was validated by experiments performed on the Škoda Felicia during various operational conditions. In this paper the authors present a parametric study investigating influence of material properties on a car cabin environment. The Matlab version of the car cabin heat load model has been developed and used. The model was extended by simple graphical user interface and it was deployed into the stand alone executable application. The aim of this parametric study is to identify most important material properties and its effect on the cabin environment during specific operational conditions of car. By means of a sensitive analysis it can identified which material parameters have to be defined precisely and which parameters are not so important for the prediction of the air temperature inside cabin.

Mixing Ventilation System in a Single-Aisle Aircraft Cabin

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm; Zhang, Chen; Wojcik, Kamil

2014-01-01

. It is also proven possible to create an acceptable draught level in the cabin. Experiments with tracer gas indicated that the contaminant from exhalation of one manikin is fully mixed in the cabin, and the experiment with personalised ventilation did not show much improvement in this situation....

Towards an Integrated Approach to Cabin Service English Curriculum Design: A Case Study of China Southern Airlines' Cabin Service English Training Course

Science.gov (United States)

Xiaoqin, Liu; Wenzhong, Zhu

2016-01-01

This paper has reviewed the history of EOP (training) development and then illustrated the curriculum design of cabin service English training from the three perspectives of ESP, CLIL and Business Discourse. It takes the cabin crew English training of China Southern Airlines (CZ) as the case and puts forward an operational framework composed of…

Increasing EDV Range through Intelligent Cabin Air Handling Strategies: Annual Progress Report

Energy Technology Data Exchange (ETDEWEB)

Leighton, Daniel [National Renewable Energy Lab. (NREL), Golden, CO (United States); Rugh, John [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-08-01

Computational fluid dynamics (CFD) simulations of a Ford Focus Electric demonstrated that a split flow heating, ventilating and air conditioning (HVAC) system with rear recirculation ducts can reduce cabin heating loads by up to 57.4% relative to full fresh air usage under some conditions (steady state, four passengers, ambient temperature of -5 deg C). Simulations also showed that implementing a continuous recirculation fraction control system into the original equipment manufacturer (OEM) HVAC system can reduce cabin heating loads by up to 50.0% relative to full fresh air usage under some conditions (steady state, four passengers, ambient temperature of -5 deg C). Identified that continuous fractional recirculation control of the OEM system can provide significant energy savings for EVs at minimal additional cost, while a split flow HVAC system with rear recirculation ducts only provides minimal additional improvement at significant additional cost.

Future aircraft cabins and design thinking: optimisation vs. win-win scenarios

Directory of Open Access Journals (Sweden)

A. Hall

2013-06-01

Full Text Available With projections indicating an increase in mobility over the next few decades and annual flight departures expected to rise to over 16 billion by 2050, there is a demand for the aviation industry and associated stakeholders to consider new forms of aircraft and technology. Customer requirements are recognized as a key driver in business. The airline is the principal customer for the aircraft manufacture. The passenger is, in turn, the airline's principal customer but they are just one of several stakeholders that include aviation authorities, airport operators, air-traffic control and security agencies. The passenger experience is a key differentiator used by airlines to attract and retain custom and the fuselage that defines the cabin envelope for the in-flight passenger experience and cabin design therefore receives significant attention for new aircraft, service updates and refurbishments. Decision making in design is crucial to arriving at viable and worthwhile cabin formats. Too little innovation will result in an aircraft manufacturer and airlines using its products falling behind its competitors. Too much may result in an over-extension with, for example, use of immature technologies that do not have the necessary reliability for a safety critical industry or sufficient value to justify the development effort. The multiple requirements associated with cabin design, can be viewed as an area for optimisation, accepting trade-offs between the various parameters. Good design, however, is often defined as developing a concept that resolves the contradictions and takes the solution towards a win-win scenario. Indeed our understanding and practice of design allows for behaviors that enhance design thinking through divergence and convergence, the use of abductive reasoning, experimentation and systems thinking. This paper explores and defines the challenges of designing the aircraft cabin of the future that will deliver on the multiple

Computational Fluid Dynamic Analysis of Enhancing Passenger Cabin Comfort Using PCM

Science.gov (United States)

Purusothaman, M.; Valarmathi, T. N.; Dada Mohammad, S. K.

2016-09-01

The main purpose of this study is to determine a cost effective way to enhance passenger cabin comfort by analyzing the effect of solar radiation of a open parked vehicle, which is exposed to constant solar radiation on a hot and sunny day. Maximum heat accumulation occurs in the car cabin due to the solar radiation. By means of computational fluid dynamics (CFD) analysis, a simulation process is conducted for the thermal regulation of the passenger cabin using a layer of phase change material (PCM) on the roof structure of a stationary car when exposed to ambient temperature on a hot sunny day. The heat energy accumulated in the passenger cabin is absorbed by a layer of PCM for phase change process. The installation of a ventilation system which uses an exhaust fan to create a natural convection scenario in the cabin is also considered to enhance passenger comfort along with PCM.

Noise-control needs in the developing energy technologies

Energy Technology Data Exchange (ETDEWEB)

Keast, D.N.

1978-03-01

The noise characteristics of existing energy conversion technologies, e.g., from obtaining and processing fossil fuels to power plants operations, and of developing energy technologies (wind, geothermal sources, solar energy or fusion systems) are discussed in terms of the effects of noise on humans, animals, structures, and equipment and methods for noise control. Regulations for noise control are described. Recommendations are made for further research on noise control and noise effects. (LCL)

Apollo Soyuz mission, toxic gas entered cabin during earth landing sequence

Science.gov (United States)

1975-01-01

A postflight analysis is presented of the sequence which caused toxic gas to enter the cabin during repressurization for 30 seconds from manual deployment of the drogue parachutes at 18,550 feet to disabling of the reaction control system at 9600 feet. Results and conclusions are discussed.

Tracking reliability for space cabin-borne equipment in development by Crow model.

Science.gov (United States)

Chen, J D; Jiao, S J; Sun, H L

2001-12-01

Objective. To study and track the reliability growth of manned spaceflight cabin-borne equipment in the course of its development. Method. A new technique of reliability growth estimation and prediction, which is composed of the Crow model and test data conversion (TDC) method was used. Result. The estimation and prediction value of the reliability growth conformed to its expectations. Conclusion. The method could dynamically estimate and predict the reliability of the equipment by making full use of various test information in the course of its development. It offered not only a possibility of tracking the equipment reliability growth, but also the reference for quality control in manned spaceflight cabin-borne equipment design and development process.

Noise control in aeroacoustics; Proceedings of the 1993 National Conference on Noise Control Engineering, NOISE-CON 93, Williamsburg, VA, May 2-5, 1993

Science.gov (United States)

Hubbard, Harvey H. (Editor)

1993-01-01

In the conference over 100 papers were presented in eight sessions: (1) Emission: Noise Sources; (2) Physical Phenomena; (3) Noise ControlElements; (4) Vibration and Shock: Generation, Transmission, Isolation, and Reduction; (5) Immission: Physical Aspects of Environmental Noise; (6) Immission: Effects of Noise; (7) Analysis; and (8) Requirements. In addition, the distinguished lecture series included presentations on the High Speed Civil Transport and on research from the United Kingdom on aircraft noise effects.

Propagation Measurements and Comparison with EM Techniques for In-Cabin Wireless Networks

Directory of Open Access Journals (Sweden)

Nektarios Moraitis

2009-01-01

Full Text Available This paper presents results of a narrowband measurement campaign conducted inside a Boeing 737–400 aircraft, the objective being the development of a propagation prediction model which can be used in the deployment of in-cabin wireless networks. The measurements were conducted at three different frequency bands: 1.8, 2.1, and 2.45 GHz, representative of several wireless services. Both a simple, empirical, inverse distance power law and a deterministic, site-specific model were investigated. Parameters for the empirical model were extracted from the measurements at different locations inside the cabin: aisle and seats. Additionally, a statistical characterization of the multipath scenario created by the transmitted signal and the various cabin elements is presented. The deterministic model, based on Physical Optics (PO techniques, provides a reasonable match with the empirical results. Finally, measurements and modeling results are provided for the penetration loss into the cabin (or out of the cabin, representative of interference scenarios.

Aerospace toxicology overview: aerial application and cabin air quality.

Science.gov (United States)

Chaturvedi, Arvind K

2011-01-01

Aerospace toxicology is a rather recent development and is closely related to aerospace medicine. Aerospace toxicology can be defined as a field of study designed to address the adverse effects of medications, chemicals, and contaminants on humans who fly within or outside the atmosphere in aviation or on space flights. The environment extending above and beyond the surface of the Earth is referred to as aerospace. The term aviation is frequently used interchangeably with aerospace. The focus of the literature review performed to prepare this paper was on aerospace toxicology-related subject matters, aerial application and aircraft cabin air quality. Among the important topics addressed are the following: · Aerial applications of agricultural chemicals, pesticidal toxicity, and exposures to aerially applied mixtures of chemicals and their associated formulating solvents/surfactants The safety of aerially encountered chemicals and the bioanalytical methods used to monitor exposures to some of them · The presence of fumes and smoke, as well as other contaminants that may generally be present in aircraft/space vehicle cabin air · And importantly, the toxic effects of aerially encountered contaminants, with emphasis on the degradation products of oils, fluids, and lubricants used in aircraft, and finally · Analytical methods used for monitoring human exposure to CO and HCN are addressed in the review, as are the signs and symptoms associated with exposures to these combustion gases. Although many agricultural chemical monitoring studies have been published, few have dealt with the occurrence of such chemicals in aircraft cabin air. However, agricultural chemicals do appear in cabin air; indeed, attempts have been made to establish maximum allowable concentrations for several of the more potentially toxic ones that are found in aircraft cabin air. In this article, I emphasize the need for precautionary measures to be taken to minimize exposures to aerially

Spacecraft Cabin Particulate Monitor, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...

Induced Noise Control

National Research Council Canada - National Science Library

Maidanik, G

2002-01-01

The induced noise control parameter is defined in terms of the ratio of the stored energy in a master dynamic system, when it is coupled to an adjunct dynamic system, to that stored energy when the coupling is absent...

Spacecraft Cabin Particulate Monitor, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...

Experimental Study of Interior Temperature Distribution Inside Parked Automobile Cabin

Directory of Open Access Journals (Sweden)

Issam Mohammed Ali Aljubury

2015-03-01

Full Text Available Temperature inside the vehicle cabin is very important to provide comfortable conditions to the car passengers. Temperature inside the cabin will be increased, when the car is left or parked directly under the sunlight. Experimental studies were performed in Baghdad, Iraq (33.3 oN, 44.4 oE to investigate the effects of solar radiation on car cabin components (dashboard, steering wheel, seat, and inside air. The test vehicle was oriented to face south to ensure maximum (thermal sun load on the front windscreen. Six different parking conditions were investigated. A suggested car cover was examined experimentally. The measurements were recorded for clear sky summer days started at 8 A.M. till 5 P.M. Results show that interior air temperature in unshaded parked car reaches 70oC and dashboard temperature can approach 100 oC. While, cardboard car shade inside the car not reduce the air temperature inside it. Suggested car cover with 1 cm part-down side windows reduced temperature of cabin components by 70 % in average compare to the base case.

The effects of the aircraft cabin environment on passengers during simulated flights

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter

2007-01-01

enables subjective assessments of the symptoms commonly experienced by passengers and crew during flights. Six investigations with subject exposure have subsequently been carried out in the aircraft cabin facility covering four environmental areas of study, i.e. humidity, air purification techniques...... but intensified complaints of headache, dizziness and claustrophobia, suggesting that air pollutants rather than low humidity cause the distress reported by airline passengers. Three investigations studying the efficacy of various air purification technologies showed that a gas phase adsorption purification unit......A 3-row, 21-seat section of a simulated Boeing 767 aircraft cabin has been built in a climate chamber, simulating the cabin environment not only in terms of materials and geometry, but also in terms of cabin air and wall temperatures and ventilation with very dry air. This realistic simulation...

Structureborne noise measurements on a small twin-engine aircraft

Science.gov (United States)

Cole, J. E., III; Martini, K. F.

1988-01-01

Structureborne noise measurements performed on a twin-engine aircraft (Beechcraft Baron) are reported. There are two overall objectives of the test program. The first is to obtain data to support the development of analytical models of the wing and fuselage, while the second is to evaluate effects of structural parameters on cabin noise. Measurements performed include structural and acoustic responses to impact excitation, structural and acoustic loss factors, and modal parameters of the wing. Path alterations include added mass to simulate fuel, variations in torque of bolts joining wing and fuselage, and increased acoustic absorption. Conclusions drawn regarding these measurements are presented.

An under-aisle air distribution system facilitating humidification of commercial aircraft cabins

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tengfei; Yin, Shi; Wang, Shugang [School of Civil and Hydraulic Engineering, Dalian University of Technology (DUT), 2 Linggong Road, Dalian 116024 (China)

2010-04-15

Air environment in aircraft cabins has long been criticized especially for the dryness of the air within. Low moisture content in cabins is known to be responsible for headache, tiredness and many other non-specific symptoms. In addition, current widely used air distribution systems on airplanes dilute internally generated pollutants by promoting air mixing and thus impose risks of infectious airborne disease transmission. To boost air humidity level while simultaneously restricting air mixing, this investigation uses a validated computational fluid dynamics (CFD) program to design a new under-aisle air distribution system for wide-body aircraft cabins. The new system supplies fully outside, dry air at low momentum through a narrow channel passage along both side cabin walls to middle height of the cabin just beneath the stowage bins, while simultaneously humidified air is supplied through both perforated under aisles. By comparing with the current mixing air distribution system in terms of distribution of relative humidity, CO{sub 2} concentration, velocity, temperature and draught risk, the new system is found being able to improve the relative humidity from the existent 10% to the new level of 20% and lessen the inhaled CO{sub 2} concentration by 30%, without causing moisture condensation on cabin interior and inducing draught risks for passengers. The water consumption rate in air humidification is only around 0.05 kg/h per person, which should be affordable by airliners. (author)

Model tracking dual stochastic controller design under irregular internal noises

International Nuclear Information System (INIS)

Lee, Jong Bok; Heo, Hoon; Cho, Yun Hyun; Ji, Tae Young

2006-01-01

Although many methods about the control of irregular external noise have been introduced and implemented, it is still necessary to design a controller that will be more effective and efficient methods to exclude for various noises. Accumulation of errors due to model tracking, internal noises (thermal noise, shot noise and l/f noise) that come from elements such as resistor, diode and transistor etc. in the circuit system and numerical errors due to digital process often destabilize the system and reduce the system performance. New stochastic controller is adopted to remove those noises using conventional controller simultaneously. Design method of a model tracking dual controller is proposed to improve the stability of system while removing external and internal noises. In the study, design process of the model tracking dual stochastic controller is introduced that improves system performance and guarantees robustness under irregular internal noises which can be created internally. The model tracking dual stochastic controller utilizing F-P-K stochastic control technique developed earlier is implemented to reveal its performance via simulation

Noise reduction in optically controlled quantum memory

Science.gov (United States)

Ma, Lijun; Slattery, Oliver; Tang, Xiao

2018-05-01

Quantum memory is an essential tool for quantum communications systems and quantum computers. An important category of quantum memory, called optically controlled quantum memory, uses a strong classical beam to control the storage and re-emission of a single-photon signal through an atomic ensemble. In this type of memory, the residual light from the strong classical control beam can cause severe noise and degrade the system performance significantly. Efficiently suppressing this noise is a requirement for the successful implementation of optically controlled quantum memories. In this paper, we briefly introduce the latest and most common approaches to quantum memory and review the various noise-reduction techniques used in implementing them.

Factors affecting ozone removal rates in a simulated aircraft cabin environment

DEFF Research Database (Denmark)

Tamas, Gyöngyi; Weschler, Charles J.; Bako-Biro, Zsolt

2006-01-01

of people, soiled T-shirts, aircraft seats and a used HEPA filter, we have been able in the course of 24 experiments to isolate the contributions of these and other factors to the removal of ozone from the cabin air. In the case of this simulated aircraft, people were responsible for almost 60% of the ozone...... present, the measured ratio of ozone's concentration in the cabin versus that outside the cabin was 0.15-0.21, smaller than levels reported in the literature. The results reinforce the conclusion that the optimal way to reduce people's exposure to both ozone and ozone oxidation products is to efficiently...

Loss of cabin pressurization in U.S. Naval aircraft: 1969-90.

Science.gov (United States)

Bason, R; Yacavone, D W

1992-05-01

During the 22-year period from 1 January 1969 to 31 December 1990, there were 205 reported cases of loss of cabin pressure in US Naval aircraft; 21 were crew-initiated and 184 were deemed accidental. The ambient altitudes varied from 10,000 ft (3048 m) to 40,000 ft. (12192 m). The most common reason for crew-initiated decompression was to clear smoke and fumes from the cockpit/cabin (95%). The most common cause for accidental loss of cabin pressure was mechanical (73.37%), with aircraft structural damage accounting for the remaining 26.63%. Serious physiological problems included 1 pneumothorax, 11 cases of Type I decompression sickness, 23 cases of mild to moderate hypoxia with no loss of consciousness, 18 cases of hypoxia with loss of consciousness, and 3 lost aircraft with 4 fatalities due to incapacitation by hypoxia. In addition, 12 ejections were attributed to loss of cockpit pressure. Nine of the ejections were deliberate and three were accidental, caused by wind blast activation of the face curtain. Three aviators lost their lives following ejection and seven aircraft were lost. While the incidence of loss of cabin pressure in Naval aircraft appears low, it none-the-less presents a definite risk to the aircrew. Lectures on the loss of cabin/cockpit pressurization should continue during indoctrination and refresher physiology training.

Prevalence of neck pain among cabin crew of Saudi Airlines.

Science.gov (United States)

Ezzat, Hesham M; Al-Sultan, Alanood; Al-Shammari, Anwar; Alyousef, Dana; Al-Hamidi, Hager; Al-Dossary, Nafla; Al-Zahrani, Nuha; Al-Abdulqader, Wala

2015-01-01

Neck pain is considered to be a major health problem in modern societies. Many previous studies found that certain occupations are related to this problem or are associated with the risk of developing it in future. Although the pain is caused by mechanical factors, it may progress to a serious problem and give rise to other abnormal symptoms such as vertigo, headache, or migraine. To investigate the prevalence of neck pain among the cabin crew of Saudi Airlines. A cross-sectional study was carried out on the available Saudi Airlines cabin crews in King Fahad Airport during our visits, using questionnaires and measurements of several parameters. Neck Pain Questionnaires were distributed to the cabin crews on Saudi Airlines and assessment sheets were completed by all participants of the study to evaluate the prevalence and distribution of neck pain. Physical therapy examination of neck motions in different directions and specific tests were performed by all the participants to identify any symptoms. Using these data the prevalence of neck pain among the cabin crews was calculated. Collected data were analyzed statistically using SPSS software calculating the mean, median, and score of the questionnaire. According to the scoring system of the study, 31 (30.09%) of 105 cabin crew staff of Saudi Airlines had neck pain. Our study confirmed a positive correlation between this occupation and neck pain, and in fact found that according to the results of logistic regression analysis, this occupation is the only significant factor that affects the positive compression test. The prevalence of neck pain among the cabin crews of Saudi Airlines was emphasized. The results show a high prevalence of neck pain in the participants of the study, with most cases appearing to run a chronic - episodic course. Further research is needed to help us understand more about the long-term course of neck pain and its broader outcomes and impacts.

Measurement and control of occupational noise

International Nuclear Information System (INIS)

Elammari, Muftah Faraj

2007-01-01

High level of environmental and occupational noise remain a problem all over the world. As problems and complaints increased dramatically by the end of the 19th and beginning of the 20th centuries focusing on the problem was intensified. In this thesis occupational noise levels at different places were measured and compared with the international permissible levels using the integrating sound level meter (Quest 2800). The calibration of the instrument was carried out before and after each measurement using the acoustic calibrator (Quest CA-12B calibrator). The method which was followed was measuring the sound pressure level of the different noise sources over a broad frequency band covering the audible frequency range using the (octave band filter, model OB-100), disregrading variation with time. Since the human ear is most sensitive in the 2-5 khz range of frequencies and least sensitive at extremely high and low frequencies the instrument was adjusted on the A weighting net work which varies with frequencies in a very similar way as that of the human ear. From the obtained results, some noise levels which were recorded were within the permissible levels i.e. below 90 dba and some noise levels were higher than the permissible limit as in janzour textile factory (95 dba), The welding workshop (120 dba), Benghazi Macaroni factory (100 dba), and near the air blowers at Zletin cement factory, Benghazi cement factory (97-10-dba) in these cases suggestions were made to minimize the problem. Concerning the noise control, four methods of noise control were tested, these methods were: reducing noise by sound absorbing material at Sirt local broadcasting radio, reducing noise by keeping a distance from the noise source, at the Boilers hall at REWDC, reducing noise by enclosures, at the compressors room at Zletin cement factory, and finally reducing noise by performing regular maintenance at Garabolli photo development centre. The percentage of noise reduction was 21%, 12

Traffic noise control of a city

International Nuclear Information System (INIS)

Ahmed, A.; Khan, J.A.; Lakhani, A.H.; Hyder, F.G.; Shamsuddin, S.A.

2003-01-01

Long exposure to noise due to traffic affects our health and comfort. A noise level up to 45 dB is acceptable for the buildings in the city. A traffic noise study was conducted in Karachi at places of high traffic flow. The noise level was between 75-85 dB. Residential and commercial buildings had sound level up to 79 dB. Reducing vehicle noise by using proper muffler and acoustic treatment should first control traffic noise. Then noise can be reduced by 10-15 dB by constructing barriers of wood or concrete along roadside. Barrier height for sound attenuation can be found from Fresnel Number. The barrier reduces noise better if width at the top is increased and an inward bend of 60 degree is placed at the top. Where feasible a 4-5 meter high concrete barrier is recommended otherwise the nearby buildings from the road should be insulated and acoustically treated. (author)

Investigating ozone-induced decomposition of surface-bound permethrin for conditions in aircraft cabins.

Science.gov (United States)

Coleman, B K; Wells, J R; Nazaroff, W W

2010-02-01

The reaction of ozone with permethrin can potentially form phosgene. Published evidence on ozone levels and permethrin surface concentrations in aircraft cabins indicated that significant phosgene formation might occur in this setting. A derivatization technique was developed to detect phosgene with a lower limit of detection of 2 ppb. Chamber experiments were conducted with permethrin-coated materials (glass, carpet, seat fabric, and plastic) exposed to ozone under cabin-relevant conditions (150 ppb O(3), 4.5/h air exchange rate, means of material-balance modeling indicates that the upper limit on the phosgene level in aircraft cabins resulting from this chemistry is approximately 1 microg/m(3) or approximately 0.3 ppb. It was thus determined that phosgene formation, if it occurs in aircraft cabins, is not likely to exceed relevant, health-based phosgene exposure guidelines. Phosgene formation from ozone-initiated oxidation of permethrin in the aircraft cabin environment, if it occurs, is estimated to generate levels below the California Office of Environmental Health Hazard Assessment acute reference exposure level of 4 microg/m(3) or approximately 1 ppb.

The Airplane Cabin Microbiome.

Science.gov (United States)

Weiss, Howard; Hertzberg, Vicki Stover; Dupont, Chris; Espinoza, Josh L; Levy, Shawn; Nelson, Karen; Norris, Sharon

2018-06-06

Serving over three billion passengers annually, air travel serves as a conduit for infectious disease spread, including emerging infections and pandemics. Over two dozen cases of in-flight transmissions have been documented. To understand these risks, a characterization of the airplane cabin microbiome is necessary. Our study team collected 229 environmental samples on ten transcontinental US flights with subsequent 16S rRNA sequencing. We found that bacterial communities were largely derived from human skin and oral commensals, as well as environmental generalist bacteria. We identified clear signatures for air versus touch surface microbiome, but not for individual types of touch surfaces. We also found large flight-to-flight beta diversity variations with no distinguishing signatures of individual flights, rather a high between-flight diversity for all touch surfaces and particularly for air samples. There was no systematic pattern of microbial community change from pre- to post-flight. Our findings are similar to those of other recent studies of the microbiome of built environments. In summary, the airplane cabin microbiome has immense airplane to airplane variability. The vast majority of airplane-associated microbes are human commensals or non-pathogenic, and the results provide a baseline for non-crisis-level airplane microbiome conditions.

Open noise barriers based on sonic crystals. Advances in noise control in transport infraestructures

Energy Technology Data Exchange (ETDEWEB)

Peiro Torres, M.P.; Redondo Pastor, J.; Bravo Plana-Sala, J.M.; Sanchez Perez, J.V.

2016-07-01

Noise control is an environmental problem of first magnitude nowadays. In this work, we present a new concept of acoustic screen designed to control the specific noise generated by transport infrastructures, based on new materials called sonic crystals. These materials are formed by arrangements of acoustic scatterers in air, and provide a new and different mechanism in the fight against noise from those of the classical screens. This mechanism is usually called multiple scattering and is due to their structuring in addition to their physical properties. Due to the separation between scatterers, these barriers are transparent to air and water allowing a reduction on their foundations. Tests carried out in a wind tunnel show a reduction of 42% in the overturning momentum compared to classical barriers. The acoustical performance of these barriers is shown in this work, explaining the new characteristics provided in the control of noise. Finally, an example of these barriers is presented and classified according to acoustic standardization tests. The acoustic barrier reported in this work provides a high technological solution in the field of noise control. (Author)

International Space Station Common Cabin Air Assembly Condensing Heat Exchanger Hydrophilic Coating Operation, Recovery, and Lessons Learned

Science.gov (United States)

Balistreri, Steven F.; Steele, John W.; Caron, Mark E.; Laliberte, Yvon J.; Shaw, Laura A.

2013-01-01

The ability to control the temperature and humidity of an environment or habitat is critical for human survival. These factors are important to maintaining human health and comfort, as well as maintaining mechanical and electrical equipment in good working order to support the human and to accomplish mission objectives. The temperature and humidity of the International Space Station (ISS) United States On-orbit Segment (USOS) cabin air is controlled by the Common Cabin Air Assembly (CCAA). The CCAA consists of a fan, a condensing heat exchanger (CHX), an air/water separator, temperature and liquid sensors, and electrical controlling hardware and software. The CHX is the primary component responsible for control of temperature and humidity. The CCAA CHX contains a chemical coating that was developed to be hydrophilic and thus attract water from the humid influent air. This attraction forms the basis for water removal and therefore cabin humidity control. However, there have been several instances of CHX coatings becoming hydrophobic and repelling water. When this behavior is observed in an operational CHX in the ISS segments, the unit s ability to remove moisture from the air is compromised and the result is liquid water carryover into downstream ducting and systems. This water carryover can have detrimental effects on the ISS cabin atmosphere quality and on the health of downstream hardware. If the water carryover is severe and widespread, this behavior can result in an inability to maintain humidity levels in the USOS. This paper will describe the operation of the five CCAAs within the USOS, the potential causes of the hydrophobic condition, and the impacts of the resulting water carryover to downstream systems. It will describe the history of this behavior and the actual observed impacts to the ISS USOS. Information on mitigation steps to protect the health of future CHX hydrophilic coatings as well as remediation and recovery of the full heat exchanger will be

Proceedings of the 1986 international conference on noise control engineering. Volume 1

International Nuclear Information System (INIS)

Lotz, R.

1986-01-01

These proceedings collect papers on noise pollution. Topics include: noise sources, noise of chain conveyors in mining, control of noise sources in power plants, noise control elements, vibration, a method of noise control in a nuclear power plant, biological effects of noise, statistical audio dosimetry, and power house noise control

Study on Noise Prediction Model and Control Schemes for Substation

Science.gov (United States)

Gao, Yang; Liu, Songtao

2014-01-01

With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods. PMID:24672356

The Feasibility of Noise Control in a Soft Drink Plant

Directory of Open Access Journals (Sweden)

Fouladi Dehaghi

2016-03-01

Full Text Available Background “Noise” can be defined as any unwanted sound. Soft drink plants, which produce the raw materials used in most carbonated beverage factories, are sources of noise. Objectives This study investigated the noise pollution present in a soft drink CO2 gas injection plant, in order to present noise control measures. Materials and Methods The instructions specified by the canadian center for occupational health and safety (CCOHS were followed during the noise study, and a sound level meter, CEL.450 calibrated with CEL-110.2 based on ISO-9612 methods, was used to record the sound pressure level (SPL at each grid point. SPL was determined in weighting scales A and C. and a noise survey map of equivalent SPLs was drawn for each part. Each part of the floor area of the soft drink factory where SPL exceeded 85 dBA was identified from the noise survey map to determine the causes of high levels of noise. In order to reduce noise level in each part, the absorption coefficient, transmission loss, and noise reduction rate were calculated in the proposed control area. Results According to the study results, noise levels in a CO2 plant’s house and control room ranged from 88 to 102 dB and 79 to 82 dB (A, respectively. In order to reduce the amount of emitted noise in the CO2 plant house and control room, a noise control plan was implemented in each part of the facility; it was met with effective results. Conclusions The findings of this investigation have clearly revealed that plant workers are at risk of developing noise-induced hearing loss. However, after the implementation of a noise control plan in each part of the facility, the noise dose received by workers has significantly decreased. The need to implement a noise conservation program was established.

Retrofitting reciprocating compressors for noise control

International Nuclear Information System (INIS)

Frank, L.; Qualfe, R.

1992-01-01

The Alberta Energy Resources Conservation Board recently enacted their noise control directive ID 88-1. The effects of this regulation on the operation of an oil and gas facility are discussed, and a specific case history is presented to provide a disciplined strategy for noise attenuation retrofits. An investigation was carried out into sound sources at a reciprocating compressor gas plant, revealing several sound sources: engine exhaust stacks, engine exhaust silencer shells, direct-drive fan cooler inlets, direct drive fan cooler outlets, aerial cooler inlets and aerial cooler outlets. Details are presented of the investigative techniques and order-ranking of sources by decibel level. When controlling engine exhaust noise, silencers or mufflers are the preferred treatment. Choice of type (reactive or absorptive) and specification of acoustical performance of a silencer are discussed. The gas plant achieved noise reductions of 6-13 dB, measured at affected residences, through the use of engine exhaust silencers. 4 figs., 2 tabs

Noise control of radiological monitoring equipment

International Nuclear Information System (INIS)

Rubick, R.D.; Stevens, W.W.; Burke, L.L.

1998-01-01

Although vacuum pumps on continuous air monitors (CAMs) do not produce noise levels above regulatory limits, engineering controls were used to establish a safer work environment. Operations performed in areas where CAMs are located are highly specialized and require precision work when handling nuclear materials, heavy metals, and inert gases. Traditional methods for controlling noise such as enclosing or isolating the source and the use of personal protection equipment were evaluated. An innovative solution was found by retrofitting CAMs with air powered multistage ejectors pumps. By allowing the air to expand in several chambers to create a vacuum, one can eliminate the noise hazard altogether. In facilities with adequate pressurized air, use of these improved ejector pumps may be a cost-effective replacement for noisy vacuum pumps. A workplace designed or engineered with noise levels as low as possible or as close to background adds to increased concentration, attention to detail, and increased production

Advanced air distribution for minimizing airborne cross infection in aircraft cabin

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Dzhartov, Viktor

2012-01-01

was ventilated at 180 L/s. The concentration of Freon mixed with air exhaled by the “infected” manikin was measured. The personalized flow pushed the contaminated exhaled air backwards where it was pulled by the suction and exhausted before mixing with the cabin air. This resulted in substantial decrease...... simulated “infected” polluting passenger and another simulated “exposed” passenger. Personalized ventilation supplied clean air at 10 L/s from front against manikins’ face. Air was sucked at 10 L/s by a suction system of two nozzles positioned on the sides of “infected” manikin’s head. The cabin...... of the tracer gas concentration in the air inhaled by the “exposed” manikin and the exhausted cabin air....

Flow and Noise Control: Review and Assessment of Future Directions

Science.gov (United States)

Thomas, Russell H.; Choudhari, Meelan M.; Joslin, Ronald D.

2002-01-01

Technologies for developing radically new aerovehicles that would combine quantum leaps in cost, safety, and performance benefits with environmental friendliness have appeared on the horizon. This report provides both an assessment of the current state-of-the-art in flow and noise control and a vision for the potential gains to be made, in terms of performance benefit for civil and military aircraft and a unique potential for noise reduction, via future advances in flow and noise technologies. This report outlines specific areas of research that will enable the breakthroughs necessary to bring this vision to reality. Recent developments in many topics within flow and noise control are reviewed. The flow control overview provides succinct summaries of various approaches for drag reduction and improved maneuvering. Both exterior and interior noise problems are examined, including dominant noise sources, physics of noise generation and propagation, and both established and proposed concepts for noise reduction. Synergy between flow and noise control is a focus and, more broadly, the need to pursue research in a more concurrent approach involving multiple disciplines. Also discussed are emerging technologies such as nanotechnology that may have a significant impact on the progress of flow and noise control.

Test of Different Air Distribution Concepts for a Single-Aisle Aircraft Cabin

DEFF Research Database (Denmark)

Nielsen, Peter V.; Damsgaard, Charlotte; Liu, Li

2013-01-01

Traditionally, air is supplied to the aircraft cabin either by individual nozzles or by supply slots. The air is expected to be fully mixed in the cabin, and the system is considered to be a mixing ventilation system. This paper will describe different air distribution systems known from other ap...

Compressor noise control begins with design--Part 1

International Nuclear Information System (INIS)

Frank, L.

1993-01-01

This paper describes the typical methods used by oil and gas pipeline companies to reduce the noise level associated with their pump and compressor stations. The common method is for the design engineer to specify an acceptable noise level at a specified distance. Unfortunately, the results by this method are rarely acceptable because vendors have not considered the effects of sound propagation outside the station, the owners have not considered the cumulative effect of various machinery, and there is little methodology available to distinguish the individual components which might be contributing the acoustically unacceptable noise levels in a multi-component system. This article stresses balanced noise control designs using noise control engineering

Pressure-equalizing earplugs do not prevent barotrauma on descent from 8000 ft cabin altitude.

Science.gov (United States)

Klokker, Mads; Vesterhauge, Søren; Jansen, Erik C

2005-11-01

The aim of this study was to evaluate the effect of pressure-equalizing earplugs available in major airports and drugstores. No previous study has focused on preventing barotrauma using these earplugs. Blinded and double-blinded, one type of pressure-equalizing earplugs (JetEars) was studied in 27 volunteers disposed to ear barotrauma. They acted as their own controls with an active earplug in one ear and a placebo earplug in the other ear at random. All were exposed to the same well-defined pressure profile for 1 h at 8000 ft, comparable to the environment in civil commercial air travel in a pressurized cabin. Satisfaction was assessed by questionnaire and objective results were evaluated prior to and after the pressure exposure by tympanometry and otoscopy using the Teed classification. The majority of the volunteers (78%) reported a pleasant noise-reducing feeling using the earplugs. However, 75% also experienced ear pain during descent. In comparing the middle ear pressure before and after pressurization, a decrease was found in ears with both active earplugs and placebo earplugs. No difference between the active and the placebo earplugs were found. Furthermore, after evaluation of the two groups of ears using otoscopy, no prevention of barotrauma was found. In fact, the ears using an active pressure-equalizing earplug scored significantly worse (p = 0.033). Feelings of noise reduction were reported, but no prevention of barotrauma could be demonstrated with the use of pressure-equalizing earplugs. Pressure-equalizing earplugs cannot be recommended in air travel for preventing ear barotrauma.

Improving driver comfort in commercial vehicles : modeling and control of a low-power active cabin suspension system

NARCIS (Netherlands)

Evers, W.J.E.

2010-01-01

Comfort enhancement of commercial vehicles has been an engineering topic ever since the first trucks emerged around 1900. Since then, significant improvements have been made by implementing cabin (secondary) and seat suspensions. Moreover, the invention of the air spring and its application to the

Occupant evaluation of 7-hour exposures in a simulated aircraft cabin - Part 2: Thermal effects

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Wyon, David Peter; Zukowska, Daria

2005-01-01

Experiments were carried out in a simulated section of an aircraft cabin with 21 seats installed in a climate chamber, to determine the extent to which passengers’ perception of cabin air quality is affected by air temperature. The temperature inside the cabin was set at three differ-ent levels, 20......, and thermal sensation - the lower the temperature, the higher the perceived air quality and freshness....

An evaluation of an airline cabin safety education program for elementary school children.

Science.gov (United States)

Liao, Meng-Yuan

2014-04-01

The knowledge, attitude, and behavior intentions of elementary school students about airline cabin safety before and after they took a specially designed safety education course were examined. A safety education program was designed for school-age children based on the cabin safety briefings airlines given to their passengers, as well as on lessons learned from emergency evacuations. The course is presented in three modes: a lecture, a demonstration, and then a film. A two-step survey was used for this empirical study: an illustrated multiple-choice questionnaire before the program, and, upon completion, the same questionnaire to assess its effectiveness. Before the program, there were significant differences in knowledge and attitude based on school locations and the frequency that students had traveled by air. After the course, students showed significant improvement in safety knowledge, attitude, and their behavior intention toward safety. Demographic factors, such as gender and grade, also affected the effectiveness of safety education. The study also showed that having the instructor directly interact with students by lecturing is far more effective than presenting the information using only video media. A long-term evaluation, the effectiveness of the program, using TV or video accessible on the Internet to deliver a cabin safety program, and a control group to eliminate potential extraneous factors are suggested for future studies. Copyright © 2013 Elsevier Ltd. All rights reserved.

First Test of Fan Active Noise Control (ANC) Completed

Science.gov (United States)

2005-01-01

With the advent of ultrahigh-bypass engines, the space available for passive acoustic treatment is becoming more limited, whereas noise regulations are becoming more stringent. Active noise control (ANC) holds promise as a solution to this problem. It uses secondary (added) noise sources to reduce or eliminate the offending noise radiation. The first active noise control test on the low-speed fan test bed was a General Electric Company system designed to control either the exhaust or inlet fan tone. This system consists of a "ring source," an induct array of error microphones, and a control computer. Fan tone noise propagates in a duct in the form of spinning waves. These waves are detected by the microphone array, and the computer identifies their spinning structure. The computer then controls the "ring source" to generate waves that have the same spinning structure and amplitude, but 180 out of phase with the fan noise. This computer generated tone cancels the fan tone before it radiates from the duct and is heard in the far field. The "ring source" used in these tests is a cylindrical array of 16 flat-plate acoustic radiators that are driven by thin piezoceramic sheets bonded to their back surfaces. The resulting source can produce spinning waves up to mode 7 at levels high enough to cancel the fan tone. The control software is flexible enough to work on spinning mode orders from -6 to 6. In this test, the fan was configured to produce a tone of order 6. The complete modal (spinning and radial) structure of the tones was measured with two builtin sets of rotating microphone rakes. These rakes provide a measurement of the system performance independent from the control system error microphones. In addition, the far-field noise was measured with a semicircular array of 28 microphones. This test represents the first in a series of tests that demonstrate different active noise control concepts, each on a progressively more complicated modal structure. The tests are

Quality control in digital mammography: the noise components

Energy Technology Data Exchange (ETDEWEB)

Leyton, Fernando [Universidade de Tarapaca, Arica (Chile). Centro de Estudios en Ciencias Radiologicas; Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nogueira, Maria do Socorro, E-mail: mnogue@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Duran, Maria Paz [Clinica Alemana, Santiago (Chile). Dept. de Radiologia; Dantas, Marcelino, E-mail: marcelino@inb.gov.b [Industrias Nucleares do Brasil (INB), Caldas, MG (Brazil). Unidade de Tratamento de Minerios; Ubeda, Carlos, E-mail: cubeda@uta.c [Universidade de Tarapaca, Arica (Chile). Fac. de Ciencias de la Salud

2011-07-01

To measure the linearity of the detector and determine the noise components (quantum, electronic and structural noise) that contributed to losing image quality and to determine the signal noise ratio (SNR) and contrast noise ratio (CNR). This paper describes the results of the implementation of a protocol for quality control in digital mammography performed in two direct digital mammography equipment (Hologic, Selenia) in Santiago of Chile. Shows the results of linearity and noise analysis of the images which establishes the main cause of noise in the image of the mammogram to ensure the quality and optimize procedures. The study evaluated two digital mammography's Selenia, Hologic (DR) from Santiago, Chile. We conducted the assessment of linearity of the detector, the signal noise ratio, contrast noise ratio and was determined the contribution of different noise components (quantum, electronics and structural noise). Used different thicknesses used in clinical practice according to the protocol for quality control in digital mammography of Spanish society of medical physics and NHSBSP Equipment Report 0604 Version 3. The Selenia mammography software was used for the analysis of images and Unfors Xi detector for measuring doses. The mammography detector has a linear performance, the CNR and SNR did not comply with the Protocol for the thicknesses of 60 and 70 mm. The main contribution of the noise corresponds to the quantum noise, therefore it is necessary to adjust and optimize the mammography system. (author)

Quality control in digital mammography: the noise components

International Nuclear Information System (INIS)

Leyton, Fernando; Nogueira, Maria do Socorro; Duran, Maria Paz; Dantas, Marcelino; Ubeda, Carlos

2011-01-01

To measure the linearity of the detector and determine the noise components (quantum, electronic and structural noise) that contributed to losing image quality and to determine the signal noise ratio (SNR) and contrast noise ratio (CNR). This paper describes the results of the implementation of a protocol for quality control in digital mammography performed in two direct digital mammography equipment (Hologic, Selenia) in Santiago of Chile. Shows the results of linearity and noise analysis of the images which establishes the main cause of noise in the image of the mammogram to ensure the quality and optimize procedures. The study evaluated two digital mammography's Selenia, Hologic (DR) from Santiago, Chile. We conducted the assessment of linearity of the detector, the signal noise ratio, contrast noise ratio and was determined the contribution of different noise components (quantum, electronics and structural noise). Used different thicknesses used in clinical practice according to the protocol for quality control in digital mammography of Spanish society of medical physics and NHSBSP Equipment Report 0604 Version 3. The Selenia mammography software was used for the analysis of images and Unfors Xi detector for measuring doses. The mammography detector has a linear performance, the CNR and SNR did not comply with the Protocol for the thicknesses of 60 and 70 mm. The main contribution of the noise corresponds to the quantum noise, therefore it is necessary to adjust and optimize the mammography system. (author)

Early and late Holocene glacial fluctuations and tephrostratigraphy, Cabin Lake, Alaska

Science.gov (United States)

Zander, Paul D.; Kaufman, Darrell S.; Kuehn, Stephen C.; Wallace, Kristi L.; Anderson, R. Scott

2013-01-01

Marked changes in sediment types deposited in Cabin Lake, near Cordova, Alaska, represent environmental shifts during the early and late Holocene, including fluctuations in the terminal position of Sheridan Glacier. Cabin Lake is situated to receive meltwater during periods when the outwash plain of the advancing Sheridan Glacier had aggraded. A brief early Holocene advance from 11.2 to 11.0 cal ka is represented by glacial rock flour near the base of the sediment core. Non-glacial lake conditions were restored for about 1000 years before the water level in Cabin Lake lowered and the core site became a fen. The fen indicates drier-than-present conditions leading up to the Holocene thermal maximum. An unconformity spanning 5400 years during the mid-Holocene is overlain by peat until 1110 CE when meltwater from Sheridan Glacier returned to the basin. Three intervals of an advanced Sheridan Glacier are recorded in the Cabin Lake sediments during the late Holocene: 1110–1180, 1260–1540 and 1610–1780 CE. The sedimentary sequence also contains the first five reported tephra deposits from the Copper River delta region, and their geochemical signatures suggest that the sources are the Cook Inlet volcanoes Redoubt, Augustine and Crater Peak, and possibly Mt Churchill in the Wrangell Volcanic field.

Astronaut Ronald Sega in crew cabin

Science.gov (United States)

1994-01-01

Astronaut Ronald M. Sega suspends himself in the weightlessness aboard the Space Shuttle Discovery's crew cabin, as the Remote Manipulator System (RMS) arm holds the Wake Shield Facility (WSF) aloft. The mission specialist is co-principle investigator on the the WSF project. Note the University of Colorado, Colorado Springs banner above his head.

Broadband Shock Noise in Internally-Mixed Dual-Stream Jets

Science.gov (United States)

Bridges, James E.

2009-01-01

Broadband shock noise (BBSN) has been studied in some detail in single-flow jets and recently in dual-stream jets with separate flow exhaust systems. Shock noise is of great concern in these latter cases because of the noise created for the aircraft cabin by the underexpanded nozzle flow at cruise. Another case where shock noise is of concern is in the case of future supersonic aircraft that are expected to have bypass ratios small enough to justify internally mixed exhaust systems, and whose mission will push cycles to the point of imperfectly expanded flows. Dual-stream jets with internally mixed plume have some simplifying aspects relative to the separate flow jets, having a single shock structure given by the common nozzle pressure. This is used to separate the contribution of the turbulent shear layer to the broadband shock noise. Shock structure is held constant while the geometry and strength of the inner and merged shear layers are varying by changing splitter area ratio and core stream temperature. Flow and noise measurements are presented which document the efforts at separating the contribution of the inner shear layer to the broadband shock noise.

On the wave induced responses for a high-speed hydrofoil catamaran. Part 2. Cabin connected to hull by spring and response to vibration; Suichuyokutsuki kosoku sodotei no harochu oto ni tsuite. 2. Dokuritsu kozogata cabin to yodo oto

Energy Technology Data Exchange (ETDEWEB)

Nobukawa, H; Kitamura, M; Kawamura, T [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

1996-04-10

A high-speed hydrofoil catamaran under development has such a structure that an independent cabin is mounted on catamaran hulls, the cabin is connected with the hulls by using four soft springs, and hydrofoils are attached to the front and rear of the cabin. The structural design conception was as follows: the self-weight of the cabin is supported by lifting power of the hydrofoils while the boat is cruising; longitudinal motions of the catamaran hulls are absorbed by soft spring struts to make the motions more difficult to be transmitted into the cabin; and vibration excited by engines rotating at high speeds, attached to rear of the catamaran hulls, is not transmitted directly to the cabin structurally. A towing experiment was carried out by using divided models of about 1/10 scale in counter waves and regular waves to investigate their vibration response characteristics in waves. Furthermore, an experimental boat made of aluminum alloy with about 1/3 scale of the design boat was attached with composite structural struts made of springs and rubber parts to perform cruising experiments on an actual sea area. As a result, it was found that vibration excited by main engines in the catamaran hulls is transmitted very little to the cabin. 2 refs., 10 figs., 1 tab.

Cancelation and its simulation using Matlab according to active noise control case study of automotive noise silencer

Science.gov (United States)

Alfisyahrin; Isranuri, I.

2018-02-01

Active Noise Control is a technique to overcome noisy with noise or sound countered with sound in scientific terminology i.e signal countered with signals. This technique can be used to dampen relevant noise in accordance with the wishes of the engineering task and reducing automotive muffler noise to a minimum. Objective of this study is to develop a Active Noise Control which should cancel the noise of automotive Exhaust (Silencer) through Signal Processing Simulation methods. Noise generator of Active Noise Control is to make the opponent signal amplitude and frequency of the automotive noise. The steps are: Firstly, the noise of automotive silencer was measured to characterize the automotive noise that its amplitude and frequency which intended to be expressed. The opposed sound which having similar character with the signal source should be generated by signal function. A comparison between the data which has been completed with simulation calculations Fourier transform field data is data that has been captured on the muffler (noise silencer) Toyota Kijang Capsule assembly 2009. MATLAB is used to simulate how the signal processing noise generated by exhaust (silencer) using FFT. This opponent is inverted phase signal from the signal source 180° conducted by Instruments of Signal Noise Generators. The process of noise cancelation examined through simulation using computer software simulation. The result is obtained that attenuation of sound (noise cancellation) has a difference of 33.7%. This value is obtained from the comparison of the value of the signal source and the signal value of the opponent. So it can be concluded that the noisy signal can be attenuated by 33.7%.

Innovative Approach for Developing Spacecraft Interior Acoustic Requirement Allocation

Science.gov (United States)

Chu, S. Reynold; Dandaroy, Indranil; Allen, Christopher S.

2016-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) is an American spacecraft for carrying four astronauts during deep space missions. This paper describes an innovative application of Power Injection Method (PIM) for allocating Orion cabin continuous noise Sound Pressure Level (SPL) limits to the sound power level (PWL) limits of major noise sources in the Environmental Control and Life Support System (ECLSS) during all mission phases. PIM is simulated using both Statistical Energy Analysis (SEA) and Hybrid Statistical Energy Analysis-Finite Element (SEA-FE) models of the Orion MPCV to obtain the transfer matrix from the PWL of the noise sources to the acoustic energies of the receivers, i.e., the cavities associated with the cabin habitable volume. The goal of the allocation strategy is to control the total energy of cabin habitable volume for maintaining the required SPL limits. Simulations are used to demonstrate that applying the allocated PWLs to the noise sources in the models indeed reproduces the SPL limits in the habitable volume. The effects of Noise Control Treatment (NCT) on allocated noise source PWLs are investigated. The measurement of source PWLs of involved fan and pump development units are also discussed as it is related to some case-specific details of the allocation strategy discussed here.

Vibro-acoustic model of an active aircraft cabin window

Science.gov (United States)

Aloufi, Badr; Behdinan, Kamran; Zu, Jean

2017-06-01

This paper presents modeling and design of an active structural acoustic control (ASAC) system for controlling the low frequency sound field transmitted through an aircraft cabin window. The system uses stacked piezoelectric elements arranged in a manner to generate out-of-plane actuation point forces acting on the window panel boundaries. A theoretical vibro-acoustic model for an active quadruple-panel system is developed to characterize the dynamic behavior of the system and achieve a good understanding of the active control performance and the physical phenomena of the sound transmission loss (STL) characteristics. The quadruple-panel system represents the passenger window design used in some classes of modern aircraft with an exterior double pane of Plexiglas, an interior dust cover pane and a glazed dimmable pane, all separated by thin air cavities. The STL characteristics of identical pane window configurations with different piezoelectric actuator sets are analyzed. A parametric study describes the influence of important active parameters, such as the input voltage, number and location of the actuator elements, on the STL is investigated. In addition, a mathematical model for obtaining the optimal input voltage is developed to improve the acoustic attenuation capability of the control system. In general, the achieved results indicate that the proposed ASAC design offers a considerable improvement in the passive sound loss performance of cabin window design without significant effects, such as weight increase, on the original design. Also, the results show that the acoustic control of the active model with piezoelectric actuators bonded to the dust cover pane generates high structural vibrations in the radiating panel (dust cover) and an increase in sound power radiation. High active acoustic attenuation can be achieved by designing the ASAC system to apply active control forces on the inner Plexiglas panel or dimmable panel by installing the actuators on the

Active Noise Control Experiments using Sound Energy Flu

Science.gov (United States)

Krause, Uli

2015-03-01

This paper reports on the latest results concerning the active noise control approach using net flow of acoustic energy. The test set-up consists of two loudspeakers simulating the engine noise and two smaller loudspeakers which belong to the active noise system. The system is completed by two acceleration sensors and one microphone per loudspeaker. The microphones are located in the near sound field of the loudspeakers. The control algorithm including the update equation of the feed-forward controller is introduced. Numerical simulations are performed with a comparison to a state of the art method minimising the radiated sound power. The proposed approach is experimentally validated.

Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins.

Science.gov (United States)

Cui, W; Wu, T; Ouyang, Q; Zhu, Y

2017-01-01

Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Noise Pollution Control System in the Hospital Environment

Science.gov (United States)

Figueroa Gallo, LM; Olivera, JM

2016-04-01

Problems related to environmental noise are not a new subject, but they became a major issue to solve because of the increasing, in complexity and intensity, of human activities due technological advances. Numerous international studies had dealt with the exposure of critical patients to noisy environment such as the Neonatal Intensive Care Units; their results show that there are difficulties in the organization in the developing brain, it can damage the delicate auditory structures and can cause biorhythm disorders, specially in preterm infants. The objective of this paper is to present the development and implementation of a control system that includes technical-management-training aspects to regulate the levels of specific noise sources in the neonatal hospitalization environment. For this purpose, there were applied different tools like: observations, surveys, procedures, an electronic control device and a training program for a Neonatal Service Unit. As a result, all noise sources were identified -some of them are eliminable-; all the service stable staff categories participated voluntarily; environmental noise measurements yielded values between 62.5 and 64.6 dBA and maximum were between 86.1 and 89.7 dBA; it was designed and installed a noise control device and the staff is being trained in noise reduction best practices.

Noise Pollution Control System in the Hospital Environment

International Nuclear Information System (INIS)

Figueroa Gallo, LM; Olivera, JM

2016-01-01

Problems related to environmental noise are not a new subject, but they became a major issue to solve because of the increasing, in complexity and intensity, of human activities due technological advances. Numerous international studies had dealt with the exposure of critical patients to noisy environment such as the Neonatal Intensive Care Units; their results show that there are difficulties in the organization in the developing brain, it can damage the delicate auditory structures and can cause biorhythm disorders, specially in preterm infants. The objective of this paper is to present the development and implementation of a control system that includes technical-management-training aspects to regulate the levels of specific noise sources in the neonatal hospitalization environment. For this purpose, there were applied different tools like: observations, surveys, procedures, an electronic control device and a training program for a Neonatal Service Unit. As a result, all noise sources were identified -some of them are eliminable-; all the service stable staff categories participated voluntarily; environmental noise measurements yielded values between 62.5 and 64.6 dBA and maximum were between 86.1 and 89.7 dBA; it was designed and installed a noise control device and the staff is being trained in noise reduction best practices. (paper)

Dual direction blower system powered by solar energy to reduce car cabin temperature in open parking condition

Science.gov (United States)

Hamdan, N. S.; Radzi, M. F. M.; Damanhuri, A. A. M.; Mokhtar, S. N.

2017-10-01

El-nino phenomenon that strikes Malaysia with temperature recorded more than 35°C can lead to extreme temperature rise in car cabin up to 80°C. Various problems will arise due to this extreme rising of temperature such as the occupant are vulnerable to heat stroke, emission of benzene gas that can cause cancer due to reaction of high temperature with interior compartments, and damage of compartments in the car. The current solution available to reduce car cabin temperature including tinted of window and portable heat rejection device that are available in the market. As an alternative to reduce car cabin temperature, this project modifies the car’s air conditioning blower motor into dual direction powered by solar energy and identifies its influence to temperature inside the car, parked under scorching sun. By reducing the car cabin temperature up to 10°C which equal to 14% of reduction in the car cabin temperature, this simple proposed system aims to provide comfort to users due to its capability in improving the quality of air and moisture in the car cabin.

Perception of cabin air quality in airline crew related to air humidification, on intercontinental flights.

Science.gov (United States)

Lindgren, T; Norbäck, D; Wieslander, G

2007-06-01

The influence of air humidification in aircraft, on perception of cabin air quality among airline crew (N = 71) was investigated. In-flight investigations were performed in the forward part and in the aft part on eight intercontinental flights with one Boeing 767 individually, equipped with an evaporation humidifier combined with a dehumidifying unit, to reduce accumulation of condensed water in the wall construction. Four flights had the air humidification active when going out, and turned off on the return flight. The four others had the inverse humidification sequence. The sequences were randomized, and double blind. Air humidification increased relative air humidity (RH) by 10% in forward part, and by 3% in aft part of the cabin and in the cockpit. When the humidification device was active, the cabin air was perceived as being less dry (P = 0.008), and fresher (P = 0.002). The mean concentration of viable bacteria (77-108 cfu/m(3)), viable molds (74-84 cfu/m(3)), and respirable particles (1-8 microg/m3) was low, both during humidified and non-humidified flights. On flights with air humidification, there were less particles in the forward part of the aircraft (P = 0.01). In conclusion, RH can be slightly increased by using ceramic evaporation humidifier, without any measurable increase of microorganisms in cabin air. The cabin air quality was perceived as being better with air humidification. PRACTICAL IMPLICATION: Relative air humidity is low (10-20%) during intercontinental flights, and can be increased by using ceramic evaporation humidifier, without any measurable increase of microorganism in cabin air. Air humidification could increase the sensation of better cabin air quality.

Genetic noise control via protein oligomerization

Energy Technology Data Exchange (ETDEWEB)

Ghim, C; Almaas, E

2008-06-12

Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamical role of protein-protein associations. We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch), integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast protein binding-unbinding kinetics, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its intrinsic switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced) state from randomly being induced (uninduced). The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of phenotypically important toggle switches, and nested positive feedback loops in

Concentrations of selected contaminants in cabin air of airbus aircrafts.

Science.gov (United States)

Dechow, M; Sohn, H; Steinhanses, J

1997-07-01

The concentrations of selected air quality parameters in aircraft cabins were investigated including particle numbers in cabin air compared to fresh air and recirculation air, the microbiological contamination and the concentration of volatile organic compounds (VOC). The Airbus types A310 of Swissair and A340 of Lufthansa were used for measurements. The particles were found to be mainly emitted by the passengers, especially by smokers. Depending on recirculation filter efficiency the recirculation air contained a lower or equal amount of particles compared to the fresh air, whereas the amount of bacteria exceeded reported concentrations within other indoor spaces. The detected species were mainly non-pathogenic, with droplet infection over short distances identified as the only health risk. The concentration of volatile organic compounds (VOC) were well below threshold values. Ethanol was identified as the compound with the highest amount in cabin air. Further organics were emitted by the passengers--as metabolic products or by smoking--and on ground as engine exhaust (bad airport air quality). Cleaning agents may be the source of further compounds.

Incidence of cancer among Finnish airline cabin attendants. 1967-92

Energy Technology Data Exchange (ETDEWEB)

Pukkala, E. [Finnish Cancer Registry, Helsinki (Finland); Auvinen, A. [Finnish Centre for Radiation and Nuclear Safety (STUK), Helsinki (Finland); Wahlberg, G. [Finnish Flight Attendants Association, Helsinki (Finland)

1995-09-09

The objective was to assess whether occupational exposure among commercial airline cabin attendants are associated with risk of cancer. A significant excess of breast cancer (standardised incidence ratio 1.87 (95% confidence interval 1.15 to 2.23)) and bone cancer (15.10 (1.82 to 54.40)) was found among female workers. The risk of breast cancer was most prominent 15 years after recruitment. Risks of leukaemia (3.57 (0.43 to 12.9)) and skin melanoma (2.11 (0.43 to 6.15)) were not significantly raised. Among men, one lymphoma and one Kaposi`s sarcoma were found (expected number of cases 1.6). Although the lifestyle of cabin attendants is different from that of the reference population - for example, in terms of social status and parity - concentration of the excess risks to primary sites sensitive to radiation suggests that ionising radiation during flights may add to that cancer risk of all flight personnel. Otherwise the lifestyle of cabin attendants did not seem to affect their risks of cancer. (author).

Incidence of cancer among Finnish airline cabin attendants. 1967-92

International Nuclear Information System (INIS)

Pukkala, E.; Auvinen, A.; Wahlberg, G.

1995-01-01

The objective was to assess whether occupational exposure among commercial airline cabin attendants are associated with risk of cancer. A significant excess of breast cancer (standardised incidence ratio 1.87 (95% confidence interval 1.15 to 2.23)) and bone cancer (15.10 (1.82 to 54.40)) was found among female workers. The risk of breast cancer was most prominent 15 years after recruitment. Risks of leukaemia (3.57 (0.43 to 12.9)) and skin melanoma (2.11 (0.43 to 6.15)) were not significantly raised. Among men, one lymphoma and one Kaposi's sarcoma were found (expected number of cases 1.6). Although the lifestyle of cabin attendants is different from that of the reference population - for example, in terms of social status and parity - concentration of the excess risks to primary sites sensitive to radiation suggests that ionising radiation during flights may add to that cancer risk of all flight personnel. Otherwise the lifestyle of cabin attendants did not seem to affect their risks of cancer. (author)

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air.

Science.gov (United States)

Jung, Heejung S; Grady, Michael L; Victoroff, Tristan; Miller, Arthur L

2017-07-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO 2 ) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO 2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm 3 , although CO 2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO 2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm 3 . We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO 2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO 2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO 2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO 2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO 2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO 2 accumulation.

An intervention for noise control of blast furnace in steel industry.

Science.gov (United States)

Golmohammadi, Rostam; Giahi, Omid; Aliabadi, Mohsen; Darvishi, Ebrahim

2014-01-01

Noise pollution is currently a major health risk factor for workers in industries. The aim of this study was to investigate noise pollution and implement a control intervention plan for blast furnace in a steel industry. The measurement of sound pressure level (SPL) along with frequency analysis was done with the sound-level-meter Cell-450. Personal noise exposure was performed using dosimeter TES-1345 calibrated with CEL-282. Before planning noise controls, acoustic insulation properties of the furnace control unit and workers' rest room were assessed. Control room and workers' rest room were redesigned in order to improve acoustical condition. The SPL before intervention around the Blast Furnace was 90.3 dB (L) and its dominant frequency was 4000 Hz. Besides, noise transmission loss of the control and rest rooms were 10.3 dB and 4.2 dB, respectively. After intervention, noise reduction rates in the control and rest rooms were 27.4 dB and 27.7 dB, respectively. The workers' noise dose before and after the intervention was 240% and less than 100%, respectively. Improvement the workroom acoustic conditions through noise insulation can be considered effective method for preventing workers exposure to harmful noise.

Reduction of external noise of mobile energy facilities by using active noise control system in muffler

Science.gov (United States)

Polivaev, O. I.; Kuznetsov, A. N.; Larionov, A. N.; Beliansky, R. G.

2018-03-01

The paper describes a method for the reducing emission of low-frequency noise of modern automotive vehicles into the environment. The importance of reducing the external noise of modern mobile energy facilities made in Russia is substantiated. Standard methods for controlling external noise in technology are of low efficiency when low-frequency sound waves are reduced. In this case, it is in the low-frequency zone of the sound range that the main power of the noise emitted by the machinery lies. The most effective way to reduce such sound waves is to use active noise control systems. A design of a muffler using a similar system is presented. This muffler allowed one to reduce the emission of increased noise levels into the environment by 7-11 dB and to increase acoustic comfort at the operator's workplace by 3-5 dB.

Quantum control with noisy fields: computational complexity versus sensitivity to noise

International Nuclear Information System (INIS)

Kallush, S; Khasin, M; Kosloff, R

2014-01-01

A closed quantum system is defined as completely controllable if an arbitrary unitary transformation can be executed using the available controls. In practice, control fields are a source of unavoidable noise, which has to be suppressed to retain controllability. Can one design control fields such that the effect of noise is negligible on the time-scale of the transformation? This question is intimately related to the fundamental problem of a connection between the computational complexity of the control problem and the sensitivity of the controlled system to noise. The present study considers a paradigm of control, where the Lie-algebraic structure of the control Hamiltonian is fixed, while the size of the system increases with the dimension of the Hilbert space representation of the algebra. We find two types of control tasks, easy and hard. Easy tasks are characterized by a small variance of the evolving state with respect to the operators of the control operators. They are relatively immune to noise and the control field is easy to find. Hard tasks have a large variance, are sensitive to noise and the control field is hard to find. The influence of noise increases with the size of the system, which is measured by the scaling factor N of the largest weight of the representation. For fixed time and control field the ability to control degrades as O(N) for easy tasks and as O(N 2 ) for hard tasks. As a consequence, even in the most favorable estimate, for large quantum systems, generic noise in the controls dominates for a typical class of target transformations, i.e. complete controllability is destroyed by noise. (paper)

Creative thinking of design and redesign on SEAT aircraft cabin testbed: a case study

NARCIS (Netherlands)

Tan, C.F.; Chen, W.; Rauterberg, G.W.M.

2009-01-01

this paper, the intuition approach in the design and redesign of the environmental friendly innovative aircraft cabin simulator is presented.. The aircraft cabin simulator is a testbed that used for European Project SEAT (Smart tEchnologies for Stress free Air Travel). The SEAT project aims to

Development of a Voice Activity Controlled Noise Canceller

Science.gov (United States)

Abid Noor, Ali O.; Samad, Salina Abdul; Hussain, Aini

2012-01-01

In this paper, a variable threshold voice activity detector (VAD) is developed to control the operation of a two-sensor adaptive noise canceller (ANC). The VAD prohibits the reference input of the ANC from containing some strength of actual speech signal during adaptation periods. The novelty of this approach resides in using the residual output from the noise canceller to control the decisions made by the VAD. Thresholds of full-band energy and zero-crossing features are adjusted according to the residual output of the adaptive filter. Performance evaluation of the proposed approach is quoted in terms of signal to noise ratio improvements as well mean square error (MSE) convergence of the ANC. The new approach showed an improved noise cancellation performance when tested under several types of environmental noise. Furthermore, the computational power of the adaptive process is reduced since the output of the adaptive filter is efficiently calculated only during non-speech periods. PMID:22778667

Development of a Voice Activity Controlled Noise Canceller

Directory of Open Access Journals (Sweden)

Aini Hussain

2012-05-01

Full Text Available In this paper, a variable threshold voice activity detector (VAD is developed to control the operation of a two-sensor adaptive noise canceller (ANC. The VAD prohibits the reference input of the ANC from containing some strength of actual speech signal during adaptation periods. The novelty of this approach resides in using the residual output from the noise canceller to control the decisions made by the VAD. Thresholds of full-band energy and zero-crossing features are adjusted according to the residual output of the adaptive filter. Performance evaluation of the proposed approach is quoted in terms of signal to noise ratio improvements as well mean square error (MSE convergence of the ANC. The new approach showed an improved noise cancellation performance when tested under several types of environmental noise. Furthermore, the computational power of the adaptive process is reduced since the output of the adaptive filter is efficiently calculated only during non-speech periods.

Vibration noise control in laser satellite communication

Science.gov (United States)

Saksonov, Avigdor; Shlomi, Arnon; Kopeika, Norman S.

2001-08-01

Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrow than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, as significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed- forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the F SM. The performances of each approach are evaluated using MATLAB simulations.

Assessment of auditory impression of the coolness and warmness of automotive HVAC noise.

Science.gov (United States)

Nakagawa, Seiji; Hotehama, Takuya; Kamiya, Masaru

2017-07-01

Noise induced by a heating, ventilation and air conditioning (HVAC) system in a vehicle is an important factor that affects the comfort of the interior of a car cabin. Much effort has been devoted to reduce noise levels, however, there is a need for a new sound design that addresses the noise problem from a different point of view. In this study, focusing on the auditory impression of automotive HVAC noise concerning coolness and warmness, psychoacoustical listening tests were performed using a paired comparison technique under various conditions of room temperature. Five stimuli were synthesized by stretching the spectral envelopes of recorded automotive HVAC noise to assess the effect of the spectral centroid, and were presented to normal-hearing subjects. Results show that the spectral centroid significantly affects the auditory impression concerning coolness and warmness; a higher spectral centroid induces a cooler auditory impression regardless of the room temperature.

Aircraft Interior Noise Control Using Distributed Piezoelectric Actuators

Science.gov (United States)

Sun, Jian Q.

1996-01-01

Developing a control system that can reduce the noise and structural vibration at the same time is an important task. This talk presents one possible technical approach for accomplishing this task. The target application of the research is for aircraft interior noise control. The emphasis of the present approach is not on control strategies, but rather on the design of actuators for the control system. In the talk, a theory of distributed piezoelectric actuators is introduced. A uniform cylindrical shell is taken as a simplified model of fuselage structures to illustrate the effectiveness of the design theory. The actuators developed are such that they can reduce the tonal structural vibration and interior noise in a wide range of frequencies. Extensive computer simulations have been done to study various aspects of the design theory. Experiments have also been conducted and the test results strongly support the theoretical development.

High-powered CO2 -lasers and noise control

Science.gov (United States)

Honkasalo, Antero; Kuronen, Juhani

High-power CO2 -lasers are being more and more widely used for welding, drilling and cutting in machine shops. In the near future, different kinds of surface treatments will also become routine practice with laser units. The industries benefitting most from high power lasers will be: the automotive industry, shipbuilding, the offshore industry, the aerospace industry, the nuclear and the chemical processing industries. Metal processing lasers are interesting from the point of view of noise control because the working tool is a laser beam. It is reasonable to suppose that the use of such laser beams will lead to lower noise levels than those connected with traditional metal processing methods and equipment. In the following presentation, the noise levels and possible noise-control problems attached to the use of high-powered CO2 -lasers are studied.

Traffic noise and vehicle movement at a controlled intersection

NARCIS (Netherlands)

Salomons, E.M.

2014-01-01

Traffic noise at an intersection controlled by traffic lights shows noise level variations due to the alternating green and red lights for the different trafficstreams. Noise peaks caused by automobiles pulling up or passing by at highspeed may be quite annoying for people living near the

Parallel feedback active noise control of MRI acoustic noise with signal decomposition using hybrid RLS-NLMS adaptive algorithms.

Science.gov (United States)

Ganguly, Anshuman; Krishna Vemuri, Sri Hari; Panahi, Issa

2014-01-01

This paper presents a cost-effective adaptive feedback Active Noise Control (FANC) method for controlling functional Magnetic Resonance Imaging (fMRI) acoustic noise by decomposing it into dominant periodic components and residual random components. Periodicity of fMRI acoustic noise is exploited by using linear prediction (LP) filtering to achieve signal decomposition. A hybrid combination of adaptive filters-Recursive Least Squares (RLS) and Normalized Least Mean Squares (NLMS) are then used to effectively control each component separately. Performance of the proposed FANC system is analyzed and Noise attenuation levels (NAL) up to 32.27 dB obtained by simulation are presented which confirm the effectiveness of the proposed FANC method.

The Interaction of Spacecraft Cabin Atmospheric Quality and Water Processing System Performance

Science.gov (United States)

Perry, Jay L.; Croomes, Scott D. (Technical Monitor)

2002-01-01

Although designed to remove organic contaminants from a variety of waste water streams, the planned U.S.- and present Russian-provided water processing systems onboard the International Space Station (ISS) have capacity limits for some of the more common volatile cleaning solvents used for housekeeping purposes. Using large quantities of volatile cleaning solvents during the ground processing and in-flight operational phases of a crewed spacecraft such as the ISS can lead to significant challenges to the water processing systems. To understand the challenges facing the management of water processing capacity, the relationship between cabin atmospheric quality and humidity condensate loading is presented. This relationship is developed as a tool to determine the cabin atmospheric loading that may compromise water processing system performance. A comparison of cabin atmospheric loading with volatile cleaning solvents from ISS, Mir, and Shuttle are presented to predict acceptable limits to maintain optimal water processing system performance.

77 FR 75600 - Policy Statement on Occupational Safety and Health Standards for Aircraft Cabin Crewmembers...

Science.gov (United States)

2012-12-21

... [Docket No. FAA-2012-0953] Policy Statement on Occupational Safety and Health Standards for Aircraft Cabin... announced a proposed policy statement regarding the regulation of some occupational safety and health conditions affecting cabin crewmembers on aircraft by the Occupational Safety and Health Administration. The...

An Evacuation Model for Passenger Ships That Includes the Influence of Obstacles in Cabins

Directory of Open Access Journals (Sweden)

Baocheng Ni

2017-01-01

Full Text Available Passenger behavior and ship environment are the key factors affecting evacuation efficiency. However, current studies ignore the interior layout of passenger ship cabins and treat the cabins as empty rooms. To investigate the influence of obstacles (e.g., tables and stools on cabin evacuation, we propose an agent-based social force model for advanced evacuation analysis of passenger ships; this model uses a goal-driven submodel to determine a plan and an extended social force submodel to govern the movement of passengers. The extended social force submodel considers the interaction forces between the passengers, crew, and obstacles and minimises the range of these forces to improve computational efficiency. We drew the following conclusions based on a series of evacuation simulations conducted in this study: (1 the proposed model endows the passenger with the behaviors of bypassing and crossing obstacles, (2 funnel-shaped exits from cabins can improve evacuation efficiency, and (3 as the exit angle increases, the evacuation time also increases. These findings offer ship designers some insight towards increasing the safety of large passenger ships.

The Perforated Curtain: Configuring the Public and the Private in Calcutta’s Cabin Culture

Directory of Open Access Journals (Sweden)

Twisha Deb

2017-04-01

Full Text Available When I was very young, eating out was not a regular activity for our family. On one of such rare occasion we ended up in a restaurant where the waiter made us sit in a cubicle with a curtain on one side. You pull the curtain and it creates a weird sense of privacy. That idea of intimate space in the middle of a busy city intrigued me. Later I found many restaurants in Kolkata where they have this sort of cabin, a private eating area. Starting from pre-independence when they were there to provide some privacy to the ladies of the family who were not allowed to eat in public, the cabin witnessed many private affairs with time, from political discussions to lovers’ silence. With changing time and the emergence of posh cafes with quirky interiors, the shabby little cabins have lost their charm, but the almost empty cabins, some even without the curtains stand there to tell a story of a time gone by.

Analyses of integrated aircraft cabin contaminant monitoring network based on Kalman consensus filter.

Science.gov (United States)

Wang, Rui; Li, Yanxiao; Sun, Hui; Chen, Zengqiang

2017-11-01

The modern civil aircrafts use air ventilation pressurized cabins subject to the limited space. In order to monitor multiple contaminants and overcome the hypersensitivity of the single sensor, the paper constructs an output correction integrated sensor configuration using sensors with different measurement theories after comparing to other two different configurations. This proposed configuration works as a node in the contaminant distributed wireless sensor monitoring network. The corresponding measurement error models of integrated sensors are also proposed by using the Kalman consensus filter to estimate states and conduct data fusion in order to regulate the single sensor measurement results. The paper develops the sufficient proof of the Kalman consensus filter stability when considering the system and the observation noises and compares the mean estimation and the mean consensus errors between Kalman consensus filter and local Kalman filter. The numerical example analyses show the effectiveness of the algorithm. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Analysis of Noise Mechanisms in Cell-Size Control.

Science.gov (United States)

Modi, Saurabh; Vargas-Garcia, Cesar Augusto; Ghusinga, Khem Raj; Singh, Abhyudai

2017-06-06

At the single-cell level, noise arises from multiple sources, such as inherent stochasticity of biomolecular processes, random partitioning of resources at division, and fluctuations in cellular growth rates. How these diverse noise mechanisms combine to drive variations in cell size within an isoclonal population is not well understood. Here, we investigate the contributions of different noise sources in well-known paradigms of cell-size control, such as adder (division occurs after adding a fixed size from birth), sizer (division occurs after reaching a size threshold), and timer (division occurs after a fixed time from birth). Analysis reveals that variation in cell size is most sensitive to errors in partitioning of volume among daughter cells, and not surprisingly, this process is well regulated among microbes. Moreover, depending on the dominant noise mechanism, different size-control strategies (or a combination of them) provide efficient buffering of size variations. We further explore mixer models of size control, where a timer phase precedes/follows an adder, as has been proposed in Caulobacter crescentus. Although mixing a timer and an adder can sometimes attenuate size variations, it invariably leads to higher-order moments growing unboundedly over time. This results in a power-law distribution for the cell size, with an exponent that depends inversely on the noise in the timer phase. Consistent with theory, we find evidence of power-law statistics in the tail of C. crescentus cell-size distribution, although there is a discrepancy between the observed power-law exponent and that predicted from the noise parameters. The discrepancy, however, is removed after data reveal that the size added by individual newborns in the adder phase itself exhibits power-law statistics. Taken together, this study provides key insights into the role of noise mechanisms in size homeostasis, and suggests an inextricable link between timer-based models of size control and

Active Control Of Structure-Borne Noise

Science.gov (United States)

Elliott, S. J.

1994-11-01

The successful practical application of active noise control requires an understanding of both its acoustic limitations and the limitations of the electrical control strategy used. This paper is concerned with the active control of sound in enclosures. First, a review is presented of the fundamental physical limitations of using loudspeakers to achieve either global or local control. Both approaches are seen to have a high frequency limit, due to either the acoustic modal overlap, or the spatial correlation function of the pressure field. These physical performance limits could, in principle, be achieved with either a feedback or a feedforward control strategy. These strategies are reviewed and the use of adaptive digital filters is discussed for both approaches. The application of adaptive feedforward control in the control of engine and road noise in cars is described. Finally, an indirect approach to the active control of sound is discussed, in which the vibration is suppressed in the structural paths connecting the source of vibration to the enclosure. Two specific examples of this strategy are described, using an active automotive engine mount and the incorporation of actuators into helicopter struts to control gear-meshing tones. In both cases good passive design can minimize the complexity of the active controller.

Applications of adaptive filters in active noise control

Science.gov (United States)

Darlington, Paul

The active reduction of acoustic noise is achieved by the addition of a cancelling acoustic signal to the unwanted sound. Successful definition of the cancelling signal amounts to a system identification problem. Recent advances in adaptive signal processing have allowed this problem to be tackled using adaptive filters, which offer significant advantages over conventional solutions. The extension of adaptive noise cancelling techniques, which were developed in the electrical signal conditioning context, to the control of acoustic systems is studied. An analysis is presented of the behavior of the Widrow-Hoff LMS adaptive noise canceller with a linear filter in its control loop. The active control of plane waves propagating axially in a hardwalled duct is used as a motivating model problem. The model problem also motivates the study of the effects of feedback around an LMS adaptive filter. An alternative stochastic gradient algorithm for controlling adaptive filters in the presence of feedback is presented.

Compressor noise control begins with design--Part 2

International Nuclear Information System (INIS)

Frank, L.

1993-01-01

Reduction of noise pollution at gas compressor stations associated with natural gas pipelines and distribution systems, has long been a complex problem. Specified noise levels of individual components tell nothing of the overall system when it is installed and placed in a site-specific setting. Further, testing for compliance performance guarantees is virtually impossible to conduct at a distant location because one cannot distinguish among various contributing noise sources. This paper develops a plan for calculating an estimate of sound generation from a compressor station and the methods for controlling and measuring sounds of individual components. It also classifies the types of noise and gives various methods of dealing with each noise type

Structural Acoustic Prediction and Interior Noise Control Technology

Science.gov (United States)

Mathur, G. P.; Chin, C. L.; Simpson, M. A.; Lee, J. T.; Palumbo, Daniel L. (Technical Monitor)

2001-01-01

This report documents the results of Task 14, "Structural Acoustic Prediction and Interior Noise Control Technology". The task was to evaluate the performance of tuned foam elements (termed Smart Foam) both analytically and experimentally. Results taken from a three-dimensional finite element model of an active, tuned foam element are presented. Measurements of sound absorption and sound transmission loss were taken using the model. These results agree well with published data. Experimental performance data were taken in Boeing's Interior Noise Test Facility where 12 smart foam elements were applied to a 757 sidewall. Several configurations were tested. Noise reductions of 5-10 dB were achieved over the 200-800 Hz bandwidth of the controller. Accelerometers mounted on the panel provided a good reference for the controller. Configurations with far-field error microphones outperformed near-field cases.

Performance Testing of a Photocatalytic Oxidation Module for Spacecraft Cabin Atmosphere Revitalization

Science.gov (United States)

Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Scott, Joseph P.; Kaiser, Mark; Seminara, Gary; Bershitsky, Alex

2011-01-01

Photocatalytic oxidation (PCO) is a candidate process technology for use in high volumetric flow rate trace contaminant control applications in sealed environments. The targeted application for PCO as applied to crewed spacecraft life support system architectures is summarized. Technical challenges characteristic of PCO are considered. Performance testing of a breadboard PCO reactor design for mineralizing polar organic compounds in a spacecraft cabin atmosphere is described. Test results are analyzed and compared to results reported in the literature for comparable PCO reactor designs.

Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios

Science.gov (United States)

Leavey, Anna; Reed, Nathan; Patel, Sameer; Bradley, Kevin; Kulkarni, Pramod; Biswas, Pratim

2017-10-01

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while travelling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5, particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst travelling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NOx, PM2.5, CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5-44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM2.5, lung-deposited SA, and CO (adj-R2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position/ventilation, and PM2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88 and 97% of cabin pollutant

Measurements of cosmic-ray doses in commercial airline cabins

International Nuclear Information System (INIS)

Okano, M.; Fujitaka, K.; Izumo, K.

1996-01-01

Cosmic radiation doses which aircrew and air passengers receive in airplanes have been calling attention in many countries especially in the last decade. In this relation, various types of information had been reported on cosmic radiation intensity. In Japan, the cosmic radiation intensity had been measured in commercial airline cabins as well as chartered flights. While the intensity depends on altitude, geomagnetic latitude (or cutoff rigidity), and temporal variation of the solar activity, their doses are often speculated based on paper records on airflights combined with the intensity-altitude relationship. In this study, however, efforts were made to estimate more realistic integrated doses in airline cabins based on actual on-board measurements which had been conducted several dozens of times in each year (e.g., 45 times in 1994 and 27 times in 1995). (author)

The Incidence and Fate of Volatile Methyl Siloxanes in a Crewed Spacecraft Cabin

Science.gov (United States)

Perry, Jay L.; Kayatin, Matthew J.

2017-01-01

Volatile methyl siloxanes (VMS) arise from diverse, pervasive sources aboard crewed spacecraft ranging from materials offgassing to volatilization from personal care products. These sources lead to a persistent VMS compound presence in the cabin environment that must be considered for robust life support system design. Volatile methyl siloxane compound stability in the cabin environment presents an additional technical issue because degradation products such as dimethylsilanediol (DMSD) are highly soluble in water leading to a unique load challenge for water purification processes. The incidence and fate of VMS compounds as observed in the terrestrial atmosphere, water, and surface (soil) environmental compartments have been evaluated as an analogy for a crewed cabin environment. Volatile methyl siloxane removal pathways aboard crewed spacecraft are discussed and a material balance accounting for a DMSD production mechanism consistent with in-flight observations is presented.

Noise Controlled Synchronization in Potassium Coupled Neural Models

DEFF Research Database (Denmark)

Postnov, D. E.; Ryazanova, L. S.; Zhirin, R. A.

2007-01-01

The paper applies biologically plausible models to investigate how noise input to small ensembles of neurons, coupled via the extracellular potassium concentration, can influence their firing patterns. Using the noise intensity and the volume of the extracellular space as control parameters, we......-temporal oscillations in neuronal ensembles....

A method for Perceptual Assessment of Automotive Audio Systems and Cabin Acoustics

DEFF Research Database (Denmark)

Kaplanis, Neofytos; Bech, Søren; Sakari, Tervo

2016-01-01

This paper reports the design and implementation of a method to perceptually assess the acoustical prop- erties of a car cabin and the subsequent sound reproduction properties of automotive audio systems. Here, we combine Spatial Decomposition Method and Rapid Sensory Analysis techniques. The for......This paper reports the design and implementation of a method to perceptually assess the acoustical prop- erties of a car cabin and the subsequent sound reproduction properties of automotive audio systems. Here, we combine Spatial Decomposition Method and Rapid Sensory Analysis techniques...

Multifunctional Coating for Crew Cabin Surfaces and Fabrics, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA's crewed spacecrafts require routine cleaning of particulate, moisture, organic, and salt contaminants on the crew cabin surfaces and fabrics. Self-cleaning...

Ozone-initiated chemistry in an occupied simulated aircraft cabin.

Science.gov (United States)

Weschler, Charles J; Wisthaler, Armin; Cowlin, Shannon; Tamás, Gyöngyi; Strøm-Tejsen, Peter; Hodgson, Alfred T; Destaillats, Hugo; Herrington, Jason; Zhang, Junfeng; Nazaroff, William W

2007-09-01

We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed section of a B-767 aircraft containing human occupants. Two separate groups of 16 females were each exposed to four conditions: low air exchange (4.4 (h-1)), exchange, 61-64 ppb ozone; high air exchange (8.8 h(-1)), exchange, 73-77 ppb ozone. The addition of ozone to the cabin air increased the levels of identified byproducts from approximately 70 to 130 ppb at the lower air exchange rate and from approximately 30 to 70 ppb at the higher air exchange rate. Most of the increase was attributable to acetone, nonanal, decanal, 4-oxopentanal (4-OPA), 6-methyl-5-hepten-2-one (6-MHO), formic acid, and acetic acid, with 0.25-0.30 mol of quantified product volatilized per mol of ozone consumed. Several of these compounds reached levels above their reported odor thresholds. Most byproducts were derived from surface reactions with occupants and their clothing, consistent with the inference that occupants were responsible for the removal of >55% of the ozone in the cabin. The observations made in this study have implications for other indoor settings. Whenever human beings and ozone are simultaneously present, one anticipates production of acetone, nonanal, decanal, 6-MHO, geranyl acetone, and 4-OPA.

Active Control of Fan Noise: Feasibility Study. Volume 3; Active Fan Noise Cancellation in the NASA Lewis Active Noise Control Fan Facility

Science.gov (United States)

Pla, Frederic G.; Hu, Ziqiang; Sutliff, Daniel L.

1996-01-01

This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests.

Phase transitions in distributed control systems with multiplicative noise

Science.gov (United States)

Allegra, Nicolas; Bamieh, Bassam; Mitra, Partha; Sire, Clément

2018-01-01

Contemporary technological challenges often involve many degrees of freedom in a distributed or networked setting. Three aspects are notable: the variables are usually associated with the nodes of a graph with limited communication resources, hindering centralized control; the communication is subject to noise; and the number of variables can be very large. These three aspects make tools and techniques from statistical physics particularly suitable for the performance analysis of such networked systems in the limit of many variables (analogous to the thermodynamic limit in statistical physics). Perhaps not surprisingly, phase-transition like phenomena appear in these systems, where a sharp change in performance can be observed with a smooth parameter variation, with the change becoming discontinuous or singular in the limit of infinite system size. In this paper, we analyze the so called network consensus problem, prototypical of the above considerations, that has previously been analyzed mostly in the context of additive noise. We show that qualitatively new phase-transition like phenomena appear for this problem in the presence of multiplicative noise. Depending on dimensions, and on the presence or absence of a conservation law, the system performance shows a discontinuous change at a threshold value of the multiplicative noise strength. In the absence of the conservation law, and for graph spectral dimension less than two, the multiplicative noise threshold (the stability margin of the control problem) is zero. This is reminiscent of the absence of robust controllers for certain classes of centralized control problems. Although our study involves a ‘toy’ model, we believe that the qualitative features are generic, with implications for the robust stability of distributed control systems, as well as the effect of roundoff errors and communication noise on distributed algorithms.

Air traffic controllers' long-term speech-in-noise training effects: A control group study.

Science.gov (United States)

Zaballos, Maria T P; Plasencia, Daniel P; González, María L Z; de Miguel, Angel R; Macías, Ángel R

2016-01-01

Speech perception in noise relies on the capacity of the auditory system to process complex sounds using sensory and cognitive skills. The possibility that these can be trained during adulthood is of special interest in auditory disorders, where speech in noise perception becomes compromised. Air traffic controllers (ATC) are constantly exposed to radio communication, a situation that seems to produce auditory learning. The objective of this study has been to quantify this effect. 19 ATC and 19 normal hearing individuals underwent a speech in noise test with three signal to noise ratios: 5, 0 and -5 dB. Noise and speech were presented through two different loudspeakers in azimuth position. Speech tokes were presented at 65 dB SPL, while white noise files were at 60, 65 and 70 dB respectively. Air traffic controllers outperform the control group in all conditions [P<0.05 in ANOVA and Mann-Whitney U tests]. Group differences were largest in the most difficult condition, SNR=-5 dB. However, no correlation between experience and performance were found for any of the conditions tested. The reason might be that ceiling performance is achieved much faster than the minimum experience time recorded, 5 years, although intrinsic cognitive abilities cannot be disregarded. ATC demonstrated enhanced ability to hear speech in challenging listening environments. This study provides evidence that long-term auditory training is indeed useful in achieving better speech-in-noise understanding even in adverse conditions, although good cognitive qualities are likely to be a basic requirement for this training to be effective. Our results show that ATC outperform the control group in all conditions. Thus, this study provides evidence that long-term auditory training is indeed useful in achieving better speech-in-noise understanding even in adverse conditions.

Applications of aero-acoustic analysis to wind turbine noise control

International Nuclear Information System (INIS)

Lowson, M.V.

1992-01-01

Wind turbine noise generation mechanisms are essentially equivalent to the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. Basic sources for the wind turbine noise radiation process are defined, and their significance assessed. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. (author)

Applications of aero-acoustic analysis to wind turbine noise control

International Nuclear Information System (INIS)

Lowson, M.

1993-01-01

Wind turbine noise generation mechanisms are essentially equivalent to the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. Basic sources for the wind turbine noise radiation process are defined, and their significance assessed. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. (author)

Noise-Induced Transition in a Voltage-Controlled Oscillator Neuron Model

International Nuclear Information System (INIS)

Xie Huizhang; Liu Xuemei; Li Zhibing; Ai Baoquan; Liu Lianggang

2008-01-01

In the presence of Gaussian white noise, we study the properties of voltage-controlled oscillator neuron model and discuss the effects of the additive and multiplicative noise. It is found that the additive noise can accelerate and counterwork the firing of neuron, which depends on the value of central frequency of neuron itself, while multiplicative noise can induce the continuous change or mutation of membrane potential

Effects of cavity resonances on sound transmission into a thin cylindrical shell. [noise reduction in aircraft fuselage

Science.gov (United States)

Koval, L. R.

1978-01-01

In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the effects of internal cavity resonances on sound transmission into a thin cylindrical shell. The 'noise reduction' of the cylinder is defined and computed, with and without including the effects of internal cavity resonances. As would be expected, the noise reduction in the absence of cavity resonances follows the same qualitative pattern as does transmission loss. Numerical results show that cavity resonances lead to wide fluctuations and a general decrease of noise reduction, especially at cavity resonances. Modest internal absorption is shown to greatly reduce the effect of cavity resonances. The effects of external airflow, internal cabin pressurization, and different acoustical properties inside and outside the cylinder are also included and briefly examined.

NOISE CONTROL IN GAS STATIONS – CASE STUDY

Directory of Open Access Journals (Sweden)

Flávio Eduardo Amaral Herzer

2010-01-01

Full Text Available The high noise level in urban has changed, in the last decades, in some way of pollution that has worried the health agents. The value registered accused levels of so high discomfort that the urban sound pollution passed to be considered as a kind of pollution that hit the outnumbered people. There are efficient measures in its control, but still there are few companies that adopt measure control and auditive conservation program. This way, the objective of the work was to evaluate the noise level in which the employees and users of the gas station are daily exposed. The survey of quantitative datum was done measuring the noise level right in the emission source and making arithmetic means with the gotten sample. The average obtained revealed that the working environment isn’t appropriate, that means the noise can affect straight to communication and working production. With the prevention objective or stabilizing the auditive lost in witch the workers and the frequenters are submitted to the referred place were proposed measures to the implantation of a Auditive Conservation Program (ACP.

Wavelet Adaptive Algorithm and Its Application to MRE Noise Control System

Directory of Open Access Journals (Sweden)

Zhang Yulin

2015-01-01

Full Text Available To address the limitation of conventional adaptive algorithm used for active noise control (ANC system, this paper proposed and studied two adaptive algorithms based on Wavelet. The twos are applied to a noise control system including magnetorheological elastomers (MRE, which is a smart viscoelastic material characterized by a complex modulus dependent on vibration frequency and controllable by external magnetic fields. Simulation results reveal that the Decomposition LMS algorithm (D-LMS and Decomposition and Reconstruction LMS algorithm (DR-LMS based on Wavelet can significantly improve the noise reduction performance of MRE control system compared with traditional LMS algorithm.

Acoustic Measurements of an Uninstalled Spacecraft Cabin Ventilation Fan Prototype

Science.gov (United States)

Koch, L. Danielle; Brown, Clifford A.; Shook, Tony D.; Winkel, James; Kolacz, John S.; Podboy, Devin M.; Loew, Raymond A.; Mirecki, Julius H.

2012-01-01

Sound pressure measurements were recorded for a prototype of a spacecraft cabin ventilation fan in a test in the NASA Glenn Acoustical Testing Laboratory. The axial fan is approximately 0.089 m (3.50 in.) in diameter and 0.223 m (9.00 in.) long and has nine rotor blades and eleven stator vanes. At design point of 12,000 rpm, the fan was predicted to produce a flow rate of 0.709 cu m/s (150 cfm) and a total pressure rise of 925 Pa (3.72 in. of water) at 12,000 rpm. While the fan was designed to be part of a ducted atmospheric revitalization system, no attempt was made to throttle the flow or simulate the installed configuration during this test. The fan was operated at six speeds from 6,000 to 13,500 rpm. A 13-microphone traversing array was used to collect sound pressure measurements along two horizontal planes parallel to the flow direction, two vertical planes upstream of the fan inlet and two vertical planes downstream of the fan exhaust. Measurements indicate that sound at blade passing frequency harmonics contribute significantly to the overall audible noise produced by the fan at free delivery conditions.

Low noise control valve

International Nuclear Information System (INIS)

Christie, R.S.

1975-01-01

Noise is one of the problems associated with the use of any type of control valve in systems involving the flow of fluids. The advent of OSHA standards has prompted control valve manufacturers to design valves with special trim to lower the sound pressure level to meet these standards. However, these levels are in some cases too high, particularly when a valve must be located in or near an area where people are working at tasks requiring a high degree of concentration. Such locations are found around and near research devices and in laboratory-office areas. This paper describes a type of fluid control device presently being used at PPL as a bypass control valve in deionized water systems and designed to reduce sound pressure levels considerably below OSHA standards. Details of the design and construction of this constant pressure drop variable flow control valve are contained in the text and are shown in photographs and drawings. Test data taken are included

Car audio using DSP for active sound control. DSP ni yoru active seigyo wo mochiita audio

Energy Technology Data Exchange (ETDEWEB)

Yamada, K.; Asano, S.; Furukawa, N. (Mitsubishi Motor Corp., Tokyo (Japan))

1993-06-01

In the automobile cabin, there are some unique problems which spoil the quality of sound reproduction from audio equipment, such as the narrow space and/or the background noise. The audio signal processing by using DSP (digital signal processor) makes enable a solution to these problems. A car audio with a high amenity has been successfully made by the active sound control using DSP. The DSP consists of an adder, coefficient multiplier, delay unit, and connections. For the actual processing by DSP, are used functions, such as sound field correction, response and processing of noises during driving, surround reproduction, graphic equalizer processing, etc. High effectiveness of the method was confirmed through the actual driving evaluation test. The present paper describes the actual method of sound control technology using DSP. Especially, the dynamic processing of the noise during driving is discussed in detail. 1 ref., 12 figs., 1 tab.

Opportunities to Reduce Air-Conditioning Loads Through Lower Cabin Soak Temperatures

International Nuclear Information System (INIS)

Farrington, R.; Cuddy, M.; Keyser, M.; Rugh, J.

1999-01-01

Air-conditioning loads can significantly reduce electric vehicle (EV) range and hybrid electric vehicle (HEV) fuel economy. In addition, a new U. S. emissions procedure, called the Supplemental Federal Test Procedure (SFTP), has provided the motivation for reducing the size of vehicle air-conditioning systems in the United States. The SFTP will measure tailpipe emissions with the air-conditioning system operating. If the size of the air-conditioning system is reduced, the cabin soak temperature must also be reduced, with no penalty in terms of passenger thermal comfort. This paper presents the impact of air-conditioning on EV range and HEV fuel economy, and compares the effectiveness of advanced glazing and cabin ventilation. Experimental and modeled results are presented

Genetic noise control via protein oligomerization

Directory of Open Access Journals (Sweden)

Almaas Eivind

2008-11-01

Full Text Available Abstract Background Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamic role of protein-protein interactions. Results We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch, integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast binding-unbinding kinetics among proteins, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its random switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced state from randomly being induced (uninduced. Conclusion The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of regulatory circuits

Poultry Plant Noise Control

Science.gov (United States)

1982-01-01

A demonstration conducted last winter at the Tip Top Poultry Plant intended to show poultry plant managers from all over the U.S. potential solutions to the problem of plant noise. Plastic covers used over sound absorbing materials need to meet cleanability requirements, high- pressure water cleaning and other harsh maintenance procedures peculiar to the poultry processing industry. For the demonstration, Fiber Flex, Inc. manufactured and donated 750 noise panels; Owens-Corning Fiberglas Corporation donated the fiberglas cores; and the cover material was purchased from Howe and Bainbridge. The Engineering Experiment Station (EES) conducted before and after noise surveys and is evaluating the effect of noise reduction on turnover and productivity in the demonstration plant. EES plans to conduct a noise abatement workshop and update a handbook to help poultry processors with noise problems. EES study and demonstration may be applicable to other food processing plants where similar sanitary constraints exist.

Noise exposure during ambulance flights and repatriation operations.

Science.gov (United States)

Küpper, Thomas E; Zimmer, Bernd; Conrad, Gerson; Jansing, Paul; Hardt, Aline

2010-01-01

Although ambulance flights are routine work and thousands of employees work in repatriation organizations, there is no data on noise exposure which may be used for preventive advice. We investigated the noise exposure of crews working in ambulance flight organizations for international patient repatriation to get the data for specific guidelines concerning noise protection. Noise levels inside Learjet 35A, the aircraft type which is most often used for repatriation operations, were collected from locations where flight crews typically spend their time. A sound level meter class 1 meeting the DIN IEC 651 requirements was used for noise measurements, but several factors during the real flight situations caused a measurement error of ~3%. Therefore, the results fulfill the specifications for class 2. The data was collected during several real repatriation operations and was combined with the flight data (hours per day) regarding the personnel to evaluate the occupationally encountered equivalent noise level according to DIN 45645-2. The measured noise levels were safely just below the 85 dB(A) threshold and should not induce permanent threshold shifts, provided that additional high noise exposure by non-occupational or private activities was avoided. As the levels of the noise produced by the engines outside the cabin are significantly above the 85 dB(A) threshold, the doors of the aircraft must be kept closed while the engines are running, and any activity performed outside the aircraft - or with the doors opened while the engines are running - must be done with adequate noise protection. The new EU noise directive (2003/10/EG) states that protective equipment must be made available to the aircrew to protect their hearing, though its use is not mandatory.

Studying the Noise Control Engineering Protocols in Industry

Directory of Open Access Journals (Sweden)

Hamid Golshah

1999-03-01

Full Text Available Today, sound is one of the detrimental factors in the workplace and its harmful impact has been so important that scientists have named it “Noise Pollutions”. Hearing is one of the five senses of human being which is also a medium for communicating with other s and enjoying the pleasant feeling of listening to a piece of music. In spite of this, changes in the intensity and frequency of sound can make it annoying. Using Sound Level Meter to measure the dB of noise in the workplace and noise control principles will be discussed here.

Automotive engine air intake system with variable noise control

Science.gov (United States)

Moenssen, David J.; Hellie, Mark D.; Koston, John D.; Shaw, Christopher E.

2005-09-01

Engine air intake systems are routinely tasked with delivering a specific target sound which involves meeting an overall noise level and, in many cases, desired frequency content over the entire engine speed range. In order to meet these targets, it is generally necessary to incorporate one or more reactive tuning devices, such as Helmholtz resonators, into the intake system. Traditional devices provide deep attenuation at their designed frequency, but they also introduce undesirable sideband resonances at a higher and a lower frequency. Even after the addition of several devices, it may still not be possible to match the desired intake noise targets due to their deep attenuation and sideband amplification. The subject of this work is to introduce an electronically controlled variable noise control (VNC) device for engine air intake systems which is capable of adjusting the air intake system's frequency response as commanded by the engine operating conditions. The VNC device permits the desired amount of attenuation of peaks in the air intake noise without introducing undesirable sideband resonances. In addition, because the tuning is controlled electronically, the VNC device can deliver a target-specific response using the same hardware across multiple vehicle programs.

Results of the Second U.S. Manned Orbital Space Flight

Science.gov (United States)

1962-05-24

malfunctioning scanner which mitter was maintained in a standby condition 6 36- Turnaround 32- -- 0Automatic Gyro window alinement . Manual 28 A ASCS...system primarily controls the environment in which the astronaut oper- ates, both in the spacecraft cabin and in the pressure suit. Total pressure... controls and other objects within the first, the clamp ring explosive bolts, and then, cabin were relative to myself. I could reach the louder noise of

The risk of melanoma in airline pilots and cabin crew: a meta-analysis.

Science.gov (United States)

Sanlorenzo, Martina; Wehner, Mackenzie R; Linos, Eleni; Kornak, John; Kainz, Wolfgang; Posch, Christian; Vujic, Igor; Johnston, Katia; Gho, Deborah; Monico, Gabriela; McGrath, James T; Osella-Abate, Simona; Quaglino, Pietro; Cleaver, James E; Ortiz-Urda, Susana

2015-01-01

Airline pilots and cabin crew are occupationally exposed to higher levels of cosmic and UV radiation than the general population, but their risk of developing melanoma is not yet established. To assess the risk of melanoma in pilots and airline crew. PubMed (1966 to October 30, 2013), Web of Science (1898 to January 27, 2014), and Scopus (1823 to January 27, 2014). All studies were included that reported a standardized incidence ratio (SIR), standardized mortality ratio (SMR), or data on expected and observed cases of melanoma or death caused by melanoma that could be used to calculate an SIR or SMR in any flight-based occupation. Primary random-effect meta-analyses were used to summarize SIR and SMR for melanoma in any flight-based occupation. Heterogeneity was assessed using the χ2 test and I2 statistic. To assess the potential bias of small studies, we used funnel plots, the Begg rank correlation test, and the Egger weighted linear regression test. Summary SIR and SMR of melanoma in pilots and cabin crew. Of the 3527 citations retrieved, 19 studies were included, with more than 266 431 participants. The overall summary SIR of participants in any flight-based occupation was 2.21 (95% CI, 1.76-2.77; P < .001; 14 records). The summary SIR for pilots was 2.22 (95% CI, 1.67-2.93; P = .001; 12 records). The summary SIR for cabin crew was 2.09 (95% CI, 1.67-2.62; P = .45; 2 records). The overall summary SMR of participants in any flight-based occupation was 1.42 (95% CI, 0.89-2.26; P = .002; 6 records). The summary SMR for pilots was 1.83 (95% CI, 1.27-2.63, P = .33; 4 records). The summary SMR for cabin crew was 0.90 (95% CI, 0.80-1.01; P = .97; 2 records). Pilots and cabin crew have approximately twice the incidence of melanoma compared with the general population. Further research on mechanisms and optimal occupational protection is needed.

Molecular bacterial diversity and bioburden of commercial airliner cabin air

Energy Technology Data Exchange (ETDEWEB)

La Duc, M.T.; Stuecker, T.; Venkateswaran, K. [California Inst. of Technology, Pasadena, CA (United States). Jet Propulsion Laboratory, Biotechnology and Planetary Protection Group

2007-11-15

Microorganisms that exist in aircraft air systems are considered to be the primary source of microbial contamination that can lead to illness shortly after flying. More than 600 million passengers board commercial airline flights annually in the United States alone. In this study, culture-independent, biomarker-targeted bacterial enumeration and identification strategies were used to estimate total bacterial burden and diversity within the cabin air of commercial airliners. Air-impingement was used to collect samples of microorganisms from 4 flights on 2 commercial carriers. The total viable microbial population ranged from below detection limits to 4.1 x 10{sup 6} cells/m{sup 3} of air. Microbes were found to gradually accumulate from the time of passenger boarding through mid-flight. A sharp decline in bacterial abundance was then observed. Representatives of the {alpha}, {beta} and {gamma} Proteobacteria, as well as Gram-positive bacteria, were isolated in varying abundance. Airline A had large abundances of Neisseria meningitidis rRNA gene sequences and Streptococcus oralis/mitis sequences. Airline B was dominated by pseudomonas synxantha sequences as well as N. meningitidis and S. oralis/mitis. The cabin air samples housed low bacterial diversity and were typically dominated by a particular subset of bacteria, notably opportunistic pathogenic inhabitants of the human respiratory tract and oral cavity. The microbes were found largely around the ventilation ducts and gasper conduits that supply cabin air. 45 refs., 4 tabs., 3 figs.

A portable solar-powered air-cooling system based on phase-change materials for a vehicle cabin

International Nuclear Information System (INIS)

Qi, Lingfei; Pan, Hongye; Zhu, Xin; Zhang, Xingtian; Salman, Waleed; Zhang, Zutao; Li, Li; Zhu, Miankuan; Yuan, Yanping; Xiang, Bo

2017-01-01

Graphical abstract: This paper proposed a portable solar-powered air cooling system for a vehicle cabin based on Phase-change Materials. The cooling system contains three main parts: a solar-energy collection module, an energy-storage module and a phase-change cooling module. The operating principle can be described as follows. For energy input, the solar-energy-collection module harvests solar energy and converts it to electricity. The power-storage module stores the electrical energy in the supercapacitor to power the electrical equipment, mainly the air pump (AP) and water pump (WP) of the phase-change cooling module. Finally, the phase-change cooling module provides cold air for the vehicle cabin to create a comfortable vehicle interior in a hot summer. The proposed system is demonstrated through thermal simulations, which show the long-duration cooling effect of the system. Temperature drops of were obtained in field tests, predicting that the proposed cooling system is beneficial and practical for cooling vehicle cabins. - Highlights: • A novel portable air cooling system based on PCMs is presented. • Solar energy was adopted to power the proposed air cooling system. • This proposed system is used for cooling vehicle cabins exposed to the sun. • Experimental results show that the proposed system has a good cooling effect. - Abstract: In summer, the temperature is very high inside vehicles parked under the hot sun. This causes consuming more fossil energy to power the air conditioner and generation of harmful gases. There is currently no effective method to address this problem in an energy-saving and environmentally friendly manner. In this paper, a novel solar-powered air-cooling system for vehicle cabins is proposed based on Phase-change Materials (PCMs); the system prevents the temperature inside a vehicle cabin from rising too high when the vehicle is parked outdoor exposure to the sun. The proposed system consists of three main parts: a solar

Ozone-Initiated Chemistry in an Occupied Simulated Aircraft Cabin

DEFF Research Database (Denmark)

Weschler, Charles J.; Wisthaler, Armin; Cowlin, Shannon

2007-01-01

We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed section of a B-767 aircraft containing human occupants. Two separate groups of 16 females were each expos...

On spatial spillover in feedforward and feedback noise control

Science.gov (United States)

Xie, Antai; Bernstein, Dennis

2017-03-01

Active feedback noise control for rejecting broadband disturbances must contend with the Bode integral constraint, which implies that suppression over some frequency range gives rise to amplification over another range at the performance microphone. This is called spectral spillover. The present paper deals with spatial spillover, which refers to the amplification of noise at locations where no microphone is located. A spatial spillover function is defined, which is valid for both feedforward and feedback control with scalar and vector control inputs. This function is numerically analyzed and measured experimentally. Obstructions are introduced in the acoustic space to investigate their effect on spatial spillover.

Advance Noise Control Fan II: Test Rig Fan Risk Management Study

Science.gov (United States)

Lucero, John

2013-01-01

Since 1995 the Advanced Noise Control Fan (ANCF) has significantly contributed to the advancement of the understanding of the physics of fan tonal noise generation. The 9'x15' WT has successfully tested multiple high speed fan designs over the last several decades. This advanced several tone noise reduction concepts to higher TRL and the validation of fan tone noise prediction codes.

Experimental study on occupant's thermal responses under the non-uniform conditions in vehicle cabin during the heating period

Science.gov (United States)

Zhang, Wencan; Chen, Jiqing; Lan, Fengchong

2014-03-01

The existing investigations on thermal comfort mostly focus on the thermal environment conditions, especially of the air-flow field and the temperature distributions in vehicle cabin. Less attention appears to direct to the thermal comfort or thermal sensation of occupants, even to the relationship between thermal conditions and thermal sensation. In this paper, a series of experiments were designed and conducted for understanding the non-uniform conditions and the occupant's thermal responses in vehicle cabin during the heating period. To accurately assess the transient temperature distribution in cabin in common daily condition, the air temperature at a number of positions is measured in a full size vehicle cabin under natural winter environment in South China by using a discrete thermocouples network. The occupant body is divided into nine segments, the skin temperature at each segment and the occupant's local thermal sensation at the head, body, upper limb and lower limb are monitored continuously. The skin temperature is observed by using a discrete thermocouples network, and the local thermal sensation is evaluated by using a seven-point thermal comfort survey questionnaire proposed by American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc(ASHRAE) Standard. The relationship between the skin temperature and the thermal sensation is discussed and regressed by statistics method. The results show that the interior air temperature is highly non-uniform over the vehicle cabin. The locations where the occupants sit have a significant effect on the occupant's thermal responses, including the skin temperature and the thermal sensation. The skin temperature and thermal sensation are quite different between body segments due to the effect of non-uniform conditions, clothing resistance, and the human thermal regulating system. A quantitative relationship between the thermal sensation and the skin temperature at each body segment of occupant in

Coupled dynamic systems and Le Chatelier's principle in noise control

Science.gov (United States)

Maidanik, G.; Becker, K. J.

2004-05-01

Investigation of coupling an externally driven dynamic system-a master dynamic system-to a passive one-an adjunct dynamic system-reveals that the response of the adjunct dynamic system affects the precoupled response of the master dynamic system. The responses, in the two dynamic systems when coupled, are estimated by the stored energies (Es) and (E0), respectively. Since the adjunct dynamic system, prior to coupling, was with zero (0) stored energy, E0s=0, the precoupled stored energy (E00) in the master dynamic system is expected to be reduced to (E0) when coupling is instituted; i.e., one expects E0noise control of the master dynamic system would result from the coupling. It is argued that the change in the disposition of the stored energies as just described may not be the only change. The coupling may influence the external input power into the master dynamic system which may interfere with the expected noise control. Indeed, the coupling may influence the external input power such that the expected beneficial noise control may not materialize. Examples of these kinds of noise control reversals are cited.

Assessment of the thermal environment in an aircraft cabin

DEFF Research Database (Denmark)

Ingers, S.; Melikov, Arsen Krikor

2004-01-01

equivalent temperature, up to 5.8°C, was identified in the outer seats. The results reveal that in an aircraft cabin, passengers in the outer seats may be exposed to thermal asymmetry and draught and may not find the thermal environment acceptable if the ventilation air is not properly supplied....

Noise filtering algorithm for the MFTF-B computer based control system

International Nuclear Information System (INIS)

Minor, E.G.

1983-01-01

An algorithm to reduce the message traffic in the MFTF-B computer based control system is described. The algorithm filters analog inputs to the control system. Its purpose is to distinguish between changes in the inputs due to noise and changes due to significant variations in the quantity being monitored. Noise is rejected while significant changes are reported to the control system data base, thus keeping the data base updated with a minimum number of messages. The algorithm is memory efficient, requiring only four bytes of storage per analog channel, and computationally simple, requiring only subtraction and comparison. Quantitative analysis of the algorithm is presented for the case of additive Gaussian noise. It is shown that the algorithm is stable and tends toward the mean value of the monitored variable over a wide variety of additive noise distributions

Control strategies for active noise barriers using near-field error sensing

NARCIS (Netherlands)

Berkhoff, Arthur P.

In this paper active noise control strategies for noise barriers are presented which are based on the use of sensors near the noise barrier. Virtual error signals are derived from these near-field sensor signals such that reductions of the far-field sound pressure are obtained with the active

Radiation Protection: The Specific Case of Cabin Crew

International Nuclear Information System (INIS)

Lecouturier, B.

1999-01-01

Exposure to cosmic radiation is one important element of the in-flight working environment. The new requirements of the Council Directive 96/29 Euratom set out basic safety standards in radiation protection which are particularly important to cabin crew. There are two major reasons why they relate specifically to this category of crew member. One is the great diversity of or in some cases the lack of, medical requirements and surveillance. The situation in this area notably differs from that relating to the cockpit crew, who have an aeronautical licence with detailed and rigid medical requirements. The other major reason is the very high percentage of women among the cabin crew (from 65% to 100% depending on the airline concerned), which emphasises the question of protection during pregnancy. The issue of radiation protection of aircrew therefore differs not only according to country and airline, but also according to the crew members concerned. The need is stressed for a harmonised application of the new requirements of the Council Directive 96/29 Euratom and, hopefully in the future, for equivalent protective provisions to be applied worldwide. (author)

Supersonic impinging jet noise reduction using a hybrid control technique

Science.gov (United States)

Wiley, Alex; Kumar, Rajan

2015-07-01

Control of the highly resonant flowfield associated with supersonic impinging jet has been experimentally investigated. Measurements were made in the supersonic impinging jet facility at the Florida State University for a Mach 1.5 ideally expanded jet. Measurements included unsteady pressures on a surface plate near the nozzle exit, acoustics in the nearfield and beneath the impingement plane, and velocity field using particle image velocimetry. Both passive control using porous surface and active control with high momentum microjet injection are effective in reducing nearfield noise and flow unsteadiness over a range of geometrical parameters; however, the type of noise reduction achieved by the two techniques is different. The passive control reduces broadband noise whereas microjet injection attenuates high amplitude impinging tones. The hybrid control, a combination of two control methods, reduces both broadband and high amplitude impinging tones and surprisingly its effectiveness is more that the additive effect of the two control techniques. The flow field measurements show that with hybrid control the impinging jet is stabilized and the turbulence quantities such as streamwise turbulence intensity, transverse turbulence intensity and turbulent shear stress are significantly reduced.

A Calculation of hydrodynamic noise of control valve on instrumentation and control system using smart plant

International Nuclear Information System (INIS)

Demon Handoyo; Djoko H Nugroho

2012-01-01

It has been calculated characteristics of the control valve Instrumentation and Control Systems using Smart Plant software. This calculation is done in order to control the valve that will be installed as part of the instrumentation and control systems to provide the performance according to the design. The characteristics that have been calculated are Reynolds number factors which are related to the flow regime in the valve. Critical pressure factor, Valve Hydrodynamic cavitation and noise index. In this paper the discussion will be limited to matters relating to Hydrodynamic noise generation process using model of the instrumentation and control system in the plant design in yellow cake PIPKPP activities in 2012. The results of the calculation of the noise on the valves design are in the range between 9.58~70.1 dBA. (author)

Control of noise - systems for compact HVAC units

DEFF Research Database (Denmark)

Pedersen, Steffen; Møller, Henrik

2012-01-01

systems affect the performance of implementations. The source pressure and the impedance of a centrifugal fan were measured, and a number of configurations for noise control were investigated. The performance of a simple analogue feedback control was tested in a physical prototype. An adaptive digital...

Multichannel active control of random noise in a small reverberant room

DEFF Research Database (Denmark)

Laugesen, Søren; Elliott, Stephen J.

1993-01-01

An algorithm for multichannel adaptive IIR (infinite impulse response) filtering is presented and applied to the active control of broadband random noise in a small reverberant room. Assuming complete knowledge of the primary noise, the theoretically optimal reductions of acoustic energy are init...... with the primary noise field generated by a panel excited by a loudspeaker in an adjoining room. These results show that far better performances are provided by IIR and FIR filters when the primary source has a lightly damped dynamic behavior which the active controller must model...

Sensor locations and noise reduction in high-purity batch distillation control loops

Directory of Open Access Journals (Sweden)

Oisiovici R.M.

2000-01-01

Full Text Available The influence of the sensor locations on the composition control of high-purity batch distillation columns has been investigated. Using concepts of the nonlinear control theory, an input-output linearizing controller was implemented to keep the distillate composition constant at a desired value by varying the reflux ratio. An Extended Kalman Filter was developed to estimate the compositions required in the control algorithm using temperature measurements. In the presence of measurement noise, the control performance depended greatly on the sensor locations. Placing the sensors further from the top stages reduced the detrimental effects of noise but increased the inference error. To achieve accurate composition control, both noise reduction and composition estimate accuracy should be considered in the selection of the sensor locations.

The effect of the descent technique and truck cabin layout on the landing impact forces.

Science.gov (United States)

Patenaude, S; Marchand, D; Samperi, S; Bélanger, M

2001-12-01

The majority of injuries to truckers are caused by falls during the descent from the cab of the truck. Several studies have shown that the techniques used to descend from the truck and the layout of the truck's cabin are the principal cause of injury. The goal of the present study was to measure the effects of the descent techniques used by the trucker and the layout of the truck's cabin on the impact forces absorbed by the lower limbs and the back. Kinematic data, obtained with the aid of a video camera, were combined with the force platform data to allow for calculation of the lower limb and L5-S1 torques as well as L5-S1 compressive forces. The trucker descended from two different conventional tractor cabin layouts. Each trucker descended from cabin using either "facing the truck" (FT) or "back to the truck" (BT) techniques. The results demonstrate that the BT technique produces greater ground impact forces than the FT technique, particularly when the truck does not have a handrail. The BT technique also causes an increase in the compressive forces exerted on the back. In conclusion, the use of the FT technique along with the aids (i.e., handrails and all the steps) help lower the landing impact forces as well as the lumbosacral compressive forces.

A hybrid SEA/modal technique for modeling structural-acoustic interior noise in rotorcraft.

Science.gov (United States)

Jayachandran, V; Bonilha, M W

2003-03-01

This paper describes a hybrid technique that combines Statistical Energy Analysis (SEA) predictions for structural vibration with acoustic modal summation techniques to predict interior noise levels in rotorcraft. The method was applied for predicting the sound field inside a mock-up of the interior panel system of the Sikorsky S-92 helicopter. The vibration amplitudes of the frame and panel systems were predicted using a detailed SEA model and these were used as inputs to the model of the interior acoustic space. The spatial distribution of the vibration field on individual panels, and their coupling to the acoustic space were modeled using stochastic techniques. Leakage and nonresonant transmission components were accounted for using space-averaged values obtained from a SEA model of the complete structural-acoustic system. Since the cabin geometry was quite simple, the modeling of the interior acoustic space was performed using a standard modal summation technique. Sound pressure levels predicted by this approach at specific microphone locations were compared with measured data. Agreement within 3 dB in one-third octave bands above 40 Hz was observed. A large discrepancy in the one-third octave band in which the first acoustic mode is resonant (31.5 Hz) was observed. Reasons for such a discrepancy are discussed in the paper. The developed technique provides a method for modeling helicopter cabin interior noise in the frequency mid-range where neither FEA nor SEA is individually effective or accurate.

Seed defective reduction in automotive Electro-Deposition Coating Process of truck cabin

Science.gov (United States)

Sonthilug, Aekkalag; Chutima, Parames

2018-02-01

The case study company is one of players in Thailand’s Automotive Industry who manufacturing truck and bus for both domestic and international market. This research focuses on a product quality problem about seed defects occurred in the Electro-Deposition Coating Process of truck cabin. The 5-phase of Six Sigma methodology including D-Define, M-Measure, A-Analyze, I-Improve, and C-Control is applied to this research to identify root causes of problem for setting new parameters of each significant factor. After the improvement, seed defects in this process is reduced from 9,178 defects per unit to 876 defects per unit (90% improvement)

Transient thermal model of passenger car's cabin and implementation to saturation cycle with alternative working fluids

International Nuclear Information System (INIS)

Lee, Hoseong; Hwang, Yunho; Song, Ilguk; Jang, Kilsang

2015-01-01

A transient thermal model of a passenger car's cabin is developed to investigate the dynamic behavior of cabin thermal conditions. The model is developed based on a lumped-parameter model and solved using integral methods. Solar radiation, engine heat through the firewall, and engine heat to the air ducts are all considered. Using the thermal model, transient temperature profiles of the interior mass and cabin air are obtained. This model is used to investigate the transient behavior of the cabin under various operating conditions: the recirculation mode in the idling state, the fresh air mode in the idling state, the recirculation mode in the driving state, and fresh air mode in the driving state. The developed model is validated by comparing with experimental data and is within 5% of deviation. The validated model is then applied for evaluating the mobile air conditioning system's design. The study found that a saturation cycle concept (four-stage cycle with two-phase refrigerant injection) could improve the system efficiency by 23.9% and reduce the power consumption by 19.3%. Lastly, several alternative refrigerants are applied and their performance is discussed. When the saturation cycle concept is applied, R1234yf MAC (mobile air conditioning) shows the largest COP (coefficient of performance) improvement and power consumption reduction. - Highlights: • The transient thermal model of the passenger car cabin is developed. • The developed model is validated with experimental data and showed 5% deviation. • Saturation cycle concept is applied to the developed cabin model. • There is 24% COP improvement by applying the saturation cycle concept. • R1234yf showed the highest potential when it is applied to the saturation cycle.

Flow and contaminant transport in an airliner cabin induced by a moving body: Model experiments and CFD predictions

Science.gov (United States)

Poussou, Stephane B.; Mazumdar, Sagnik; Plesniak, Michael W.; Sojka, Paul E.; Chen, Qingyan

2010-08-01

The effects of a moving human body on flow and contaminant transport inside an aircraft cabin were investigated. Experiments were performed in a one-tenth scale, water-based model. The flow field and contaminant transport were measured using the Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF) techniques, respectively. Measurements were obtained with (ventilation case) and without (baseline case) the cabin environmental control system (ECS). The PIV measurements show strong intermittency in the instantaneous near-wake flow. A symmetric downwash flow was observed along the vertical centerline of the moving body in the baseline case. The evolution of this flow pattern is profoundly perturbed by the flow from the ECS. Furthermore, a contaminant originating from the moving body is observed to convect to higher vertical locations in the presence of ventilation. These experimental data were used to validate a Computational Fluid Dynamic (CFD) model. The CFD model can effectively capture the characteristic flow features and contaminant transport observed in the small-scale model.

Analytical modeling of the structureborne noise path on a small twin-engine aircraft

Science.gov (United States)

Cole, J. E., III; Stokes, A. Westagard; Garrelick, J. M.; Martini, K. F.

1988-01-01

The structureborne noise path of a six passenger twin-engine aircraft is analyzed. Models of the wing and fuselage structures as well as the interior acoustic space of the cabin are developed and used to evaluate sensitivity to structural and acoustic parameters. Different modeling approaches are used to examine aspects of the structureborne path. These approaches are guided by a number of considerations including the geometry of the structures, the frequency range of interest, and the tractability of the computations. Results of these approaches are compared with experimental data.

The noise control prioritizing index in a tire manufacturing company

Directory of Open Access Journals (Sweden)

Rostam Golmohammadi

2017-11-01

Conclusion; the results of the present study indicated that using an index resulted from a combination of various parameters affecting the noise pollution, we would be able to prioritize units for implementing noise pollution control confidently. The results of the present study are applicable to all similar industrial settings.

Quantum dynamics manipulation using optimal control theory in the presence of laser field noise

Science.gov (United States)

Kumar, Praveen; Malinovskaya, Svetlana A.

2010-08-01

We discuss recent advances in optimal control theory (OCT) related to the investigation of the impact of control field noise on controllability of quantum dynamics. Two numerical methods, the gradient method and the iteration method, are paid particular attention. We analyze the problem of designing noisy control fields to maximize the vibrational transition probability in diatomic quantum systems, e.g. the HF and OH molecules. White noise is used as an additive random variable in the amplitude of the control field. It is demonstrated that the convergence is faster in the presence of noise and population transfer is increased by 0.04% for small values of noise compared to the field amplitude.

Basic data report for borehole Cabin Baby-1 deepening and hydrologic testing. Waste Isolation Pilot Plant (WIPP) project, southeastern New Mexico

International Nuclear Information System (INIS)

Beauheim, R.L.; Hassinger, B.W.; Klaiber, J.A.

1983-12-01

Borehole Cabin Baby-1 was originally drilled to a depth of 4159.0 feet below kelly bushing (8.0 feet above ground surface) in 1974 and 1975 as a ''wildcat'' hydrocarbon exploratory well. Control of the borehole was given to the US Department of Energy (DOE) after it was found to be a ''dry hole''. Cabin Baby-1 was reentered, deepened, and hydrologically tested in August and September 1983. The well is located in Section 5, T23S, R31E, just outside the limit of WIPP Zone III, approximately 2.5 miles south of the WIPP exploratory shaft. The deepening and testing of Cabin Baby-1 was undertaken for several reasons: to provide data on the hydrologic properties, including hydrostatic head potential of selected permeable zones in the Bell Canyon Formation; to provide representative fluid samples from selected permeable zones in the Bell Canyon Formation for determination of fluid composition and density; and to define further the stratigraphy of the upper Bell Canyon Formation at the Cabin Baby-1 location. The borehole was deepened from the previous total depth to a new depth of 4298.6 feet below kelly bushing by continuous coring. Field operations related to deepening and logging of the borehole began August 12, 1983 and were completed August 30, 1983. Hydrologic testing activities began August 30, 1983 and were completed September 29, 1983. Drill-stem tests were conducted in four zones in the Bell Canyon Formation, and one test of the Salado Formation was performed. Fluid samples were collected from the Hays and Olds sandstones of the Bell Canyon Formation

DETERMINATION OF AGRICULTURAL MACHINERY OPERATORS’ OPINIONS ABOUT THE CABIN COMFORT IN ESKİŞEHİR

Directory of Open Access Journals (Sweden)

Özge ACARBAŞ BALTACI

2015-08-01

Full Text Available Comfort has a great importance in the interior design of tractor and agricultural machinery cabins. Operators are exposed to muscoskeletal system disorders since they spend long time periods during the day in these vehicles. There is a few work in the literature reporting operators’ opinions about cabin comfort of these machineries. In this study, a questionnaire was conducted in order to get information about agricultural machinery operators’ opinions about the comfort of their vehicles. Tractor cabins and combine harvester machine cabins were selected as machineries. The study was conducted in Eskişehir in Turkey. Questionnaire was composed of four groups of questions and five ordered response levels were used in the Likert's scale. Demographic questions, general questions about the machine, personal evaluation questions and open ended questions were asked to the operators. After the questionnaire completed, collected data were classified according to the machine type. Frequency tables were used to present the results. Visibility and the accessibility were the most satisfied issues for the tractor operators with 55.9% and 55.4% percentages, respectively. Seat comfort has the highest satisfaction degree with 43.7% for the combine harvester operators. Cronbach Alpha reliability coefficient was used for the satisfaction questions in the applied questionnaire. The reliability of the study was high with coefficients of 0.878 and 0.940 for the tractor and combine harvester questionnaires, respectively. This study will support design and development process of new products by considering operator opinions.

Linear signal noise summer accurately determines and controls S/N ratio

Science.gov (United States)

Sundry, J. L.

1966-01-01

Linear signal noise summer precisely controls the relative power levels of signal and noise, and mixes them linearly in accurately known ratios. The S/N ratio accuracy and stability are greatly improved by this technique and are attained simultaneously.

Assessment and control design for steam vent noise in an oil refinery.

Science.gov (United States)

Monazzam, Mohammad Reza; Golmohammadi, Rostam; Nourollahi, Maryam; Momen Bellah Fard, Samaneh

2011-06-13

Noise is one of the most important harmful agents in work environment. Noise pollution in oil refinery industries is related to workers' health. This study aimed to determine the overall noise pollution of an oil refinery operation and its frequency analysis to determine the control plan for a vent noise in these industries. This experimental study performed in control unit of Tehran Oil Refinery in 2008. To determine the noise distributions, environmental noise measurements were carried out by lattice method according to basic information and technical process. The sound pressure level and frequency distribution was measured for each study sources subject separately was performed individually. According to the vent's specification, the measured steam noise characteristics reviewed and compared to the theoretical results of steam noise estimation. Eventually, a double expansion muffler was designed. Data analysis and graphical design were carried out using Excel software. The results of environmental noise measurements indicated that the level of sound pressure was above the national permitted level (85 dB (A)). The Mean level of sound pressure of the studied steam jet was 90.3 dB (L). The results of noise frequency analysis for the steam vents showed that the dominant frequency was 4000 Hz. To obtain 17 dB noise reductions, a double chamber aluminum muffler with 500 mm length and 200 mm diameter consisting pipe drilled was designed. The characteristics of steam vent noise were separated from other sources, a double expansion muffler was designed using a new method based on the level of steam noise, and principle sound frequency, a double expansion muffler was designed.

Engineering to Control Noise, Loading, and Optimal Operating Points

International Nuclear Information System (INIS)

Mitchell R. Swartz

2000-01-01

Successful engineering of low-energy nuclear systems requires control of noise, loading, and optimum operating point (OOP) manifolds. The latter result from the biphasic system response of low-energy nuclear reaction (LENR)/cold fusion systems, and their ash production rate, to input electrical power. Knowledge of the optimal operating point manifold can improve the reproducibility and efficacy of these systems in several ways. Improved control of noise, loading, and peak production rates is available through the study, and use, of OOP manifolds. Engineering of systems toward the OOP-manifold drive-point peak may, with inclusion of geometric factors, permit more accurate uniform determinations of the calibrated activity of these materials/systems

Study of air flow and temperature distribution in ship's crew cabins

Energy Technology Data Exchange (ETDEWEB)

Elsafty, A.F. [Arab Academy for Science and Technology and Maritime Transport, Alexandria (Egypt). Dept. of Mechanical and Marine Engineering; Ali, A.A.; Nasr, A.N. [Arab Academy for Science and Technology and Maritime Transport, Alexandria (Egypt). Dept. of Marine Engineering Technology

2007-07-01

Because of low internal heights in ship's crew cabins, the supplied air is directed to the persons at low mixing ratios. However, this does not allow the mixing process between the supplied air and the indoor air to be completed before the air enters human lungs. This paper presented an experimental and numerical simulation study that used computational fluid dynamics (CFD) to investigate the effect of the air supply location on thermal air diffusion in the ship's crew cabins space. The paper presented the results in terms of air diffusion performance index. The paper presented the CFD model, including selected space configurations; CFD simulation; boundary conditions; and CFD results. The CFD airflow simulation programs CFD were utilized to calculate the spatial distribution of temperature and velocity. The study focused on the typical Middle East region working vessel under thermal and boundary conditions including the high cooling load used in this region. Experimental data were also introduced to verify the CFD results package. It was concluded that the supply should be located near the high sidewall of the cabin. This gives better air distribution inside the space rather than the center of the room. 5 refs., 1 tab., 6 figs.

Quieting: A Practical Guide to Noise Control. NBS Handbook 119.

Science.gov (United States)

Berendt, Raymond D.; And Others

This guide describes the ways in which sounds are generated, travel, and affect the listener's hearing and well-being. Recommendations are given for controlling noise at the source and along its path of travel, and for protecting the listener. Remedies are given for noise commonly encountered in homes, work environments, schools, while traveling,…

Reward Pays the Cost of Noise Reduction in Motor and Cognitive Control.

Science.gov (United States)

Manohar, Sanjay G; Chong, Trevor T-J; Apps, Matthew A J; Batla, Amit; Stamelou, Maria; Jarman, Paul R; Bhatia, Kailash P; Husain, Masud

2015-06-29

Speed-accuracy trade-off is an intensively studied law governing almost all behavioral tasks across species. Here we show that motivation by reward breaks this law, by simultaneously invigorating movement and improving response precision. We devised a model to explain this paradoxical effect of reward by considering a new factor: the cost of control. Exerting control to improve response precision might itself come at a cost--a cost to attenuate a proportion of intrinsic neural noise. Applying a noise-reduction cost to optimal motor control predicted that reward can increase both velocity and accuracy. Similarly, application to decision-making predicted that reward reduces reaction times and errors in cognitive control. We used a novel saccadic distraction task to quantify the speed and accuracy of both movements and decisions under varying reward. Both faster speeds and smaller errors were observed with higher incentives, with the results best fitted by a model including a precision cost. Recent theories consider dopamine to be a key neuromodulator in mediating motivational effects of reward. We therefore examined how Parkinson's disease (PD), a condition associated with dopamine depletion, alters the effects of reward. Individuals with PD showed reduced reward sensitivity in their speed and accuracy, consistent in our model with higher noise-control costs. Including a cost of control over noise explains how reward may allow apparent performance limits to be surpassed. On this view, the pattern of reduced reward sensitivity in PD patients can specifically be accounted for by a higher cost for controlling noise. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Residential traffic noise exposure and vestibular schwannoma - a Danish case-control study.

Science.gov (United States)

Roswall, Nina; Stangerup, Sven-Eric; Cayé-Thomasen, Per; Schüz, Joachim; Johansen, Christoffer; Jensen, Steen Solvang; Raaschou-Nielsen, Ole; Sørensen, Mette

2017-10-01

Few risk factors for sporadic vestibular schwannoma (VS) are known. Several studies have proposed an increased risk with occupational noise exposure, whereas no studies have investigated residential traffic noise exposure as a risk factor. The present study investigated if residential traffic noise was associated with vestibular schwannoma in a large, population-based Danish case-control study. We identified 1454 VS cases, age above 30 years at diagnosis, between 1990 and 2007. For each case, we selected two random population controls, matched on sex and year of birth. Road and railway traffic noise at the residence was calculated for all present and historical addresses between 1987 and index date. Associations between traffic noise and risk for VS were estimated using conditional logistic regression, adjusted for education, disposable personal income, cohabitation status, railway noise exposure, municipal population density, and municipal income. A two-year time-weighted mean road traffic noise exposure was associated with an adjusted odds ratio of 0.92 (0.82-1.03) for developing VS, per 10 dB increment. There was no clear trend in categorical analyses. Similarly, linear and categorical analyses of residential railway noise did not suggest an association. We found no interaction with demographics, year of diagnosis, individual and municipal socioeconomic variables, and railway noise exposure. The results did not differ by tumor side, spread or size. The present study does not suggest an association between residential traffic noise and VS.

The development and validation of a thermal model for the cabin of a vehicle

International Nuclear Information System (INIS)

Marcos, David; Pino, Francisco J.; Bordons, Carlos; Guerra, José J.

2014-01-01

Energy management in modern vehicles is a crucial issue, especially in the case of electric vehicles (EV) or hybrid vehicles (HV), in which different energy sources and loads must be considered for the operation of a vehicle. Air conditioning is an important load that must be thoroughly analysed because it can constitute a considerable percentage of the energy demand. In this paper, a simplified and dynamic thermal model for the cabin of a vehicle is proposed and validated. The developed model can be used for the design and testing of the heating, ventilation, and air conditioning (HVAC) system of a vehicle and for the study of its effects on the performance and fuel consumption of vehicles, such as EVs or HVs. The model is based on theoretical heat transfer, thermal inertia, and radiation treatment equations. The model results obtained from simulations are compared with the cabin air temperature of a vehicle under different conditions. This comparison demonstrates the accuracy between the simulation results and actual results. - Highlights: •A thermal model of a vehicle cabin with two thermal inertias is developed. •The model is validated with experimental data. •The simulation results and the experimental data fit

Intuitive thinking of design and redesign on innovative aircraft cabin simulator

NARCIS (Netherlands)

Tan, C.F.; Chen, W.; Rauterberg, G.W.M.

2009-01-01

In this paper, the intuition approach in the design and redesign of the environmental friendly innovative aircraft cabin simulator is presented. The simulator is a testbed that was designed and built for research on aircraft passenger comfort improvement of long haul air travel. The simulation

Simulation on a car interior aerodynamic noise control based on statistical energy analysis

Science.gov (United States)

Chen, Xin; Wang, Dengfeng; Ma, Zhengdong

2012-09-01

How to simulate interior aerodynamic noise accurately is an important question of a car interior noise reduction. The unsteady aerodynamic pressure on body surfaces is proved to be the key effect factor of car interior aerodynamic noise control in high frequency on high speed. In this paper, a detail statistical energy analysis (SEA) model is built. And the vibra-acoustic power inputs are loaded on the model for the valid result of car interior noise analysis. The model is the solid foundation for further optimization on car interior noise control. After the most sensitive subsystems for the power contribution to car interior noise are pointed by SEA comprehensive analysis, the sound pressure level of car interior aerodynamic noise can be reduced by improving their sound and damping characteristics. The further vehicle testing results show that it is available to improve the interior acoustic performance by using detailed SEA model, which comprised by more than 80 subsystems, with the unsteady aerodynamic pressure calculation on body surfaces and the materials improvement of sound/damping properties. It is able to acquire more than 2 dB reduction on the central frequency in the spectrum over 800 Hz. The proposed optimization method can be looked as a reference of car interior aerodynamic noise control by the detail SEA model integrated unsteady computational fluid dynamics (CFD) and sensitivity analysis of acoustic contribution.

The Traffic Noise Index: A Method of Controlling Noise Nuisance.

Science.gov (United States)

Langdon, F. J.; Scholes, W. E.

This building research survey is an analysis of the social nuisance caused by urban motor ways and their noise. The Traffic Noise Index is used to indicate traffic noises and their effects on architectural designs and planning, while suggesting the need for more and better window insulation and acoustical barriers. Overall concern is for--(1)…

Vaporized Hydrogen Peroxide (VHP) Decontamination of a Section of a Boeing 747 Cabin

National Research Council Canada - National Science Library

Shaffstall, Robert M; Garner, Robert P; Bishop, Joshua; Cameron-Landis, Lora; Eddington, Donald L; Hau, Gwen; Spera, Shawn; Mielnik, Thaddeus; Thomas, James A

2006-01-01

The use of STERIS Corporation's Vaporized Hydrogen Peroxide (VHP)* technology as a potential biocide for aircraft decontamination was demonstrated in a cabin section of the Aircraft Environment Research Facility...

Psycho-acoustic evaluation of the indoor noise in cabins of a naval vessel using a back-propagation neural network algorithm

Directory of Open Access Journals (Sweden)

Hyung-Suk Han

2012-12-01

Full Text Available The indoor noise of a ship is usually determined using the A-weighted sound pressure level. However, in order to better understand this phenomenon, evaluation parameters that more accurately reflect the human sense of hearing are required. To find the level of the satisfaction index of the noise inside a naval vessel such as “Loudness” and “Annoyance”, psycho-acoustic evaluation of various sound recordings from the naval vessel was performed in a laboratory. The objective of this paper is to develop a single index of “Loudness” and “Annoyance” for noise inside a naval vessel according to a psycho-acoustic evaluation by using psychological responses such as Noise Rating (NR, Noise Criterion (NC, Room Criterion (RC, Preferred Speech Interference Level (PSIL and loudness level. Additionally, in order to determine a single index of satisfaction for noise such as “Loudness” and “Annoyance”, with respect to a human's sense of hearing, a back-propagation neural network is applied.

Active Electromagnetic Interference Cancelation for Automotive Switch-Mode Audio Power Amplifiers

DEFF Research Database (Denmark)

Knott, Arnold; Pfaffinger, Gerhard; Andersen, Michael A. E.

2009-01-01

Recent trends in the automotive audio industry have shown the importance of active noise cancelation (ANC) for major improvements in mobile entertainment environments. These approaches target the acoustical noise in the cabin and superimpose an inverse noise signal to cancel disturbances. Electro......Recent trends in the automotive audio industry have shown the importance of active noise cancelation (ANC) for major improvements in mobile entertainment environments. These approaches target the acoustical noise in the cabin and superimpose an inverse noise signal to cancel disturbances...

Advanced air distribution for minimizing airborne cross-infection in aircraft cabins

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Dzhartov, Viktor

2013-01-01

The performance of personalized ventilation combined with local exhaust at each seat was studied for the purpose of minimizing airborne cross-infection in spaces whose occupants are sedentary, such as transportation environments. Experiments were carried out in a simulated aircraft cabin section (3...... rows, 21 seats). One breathing thermal manikin simulated an infected passenger as a source of pollution, and a second breathing manikin simulated an exposed passenger. The personalized ventilation supplied clean air at 6 or 10 L/s (12.7 of 21.2 cfm) from in front of each manikin's face. Air...... was withdrawn at a rate of 6 or 10 L/s (12.7 or (21.2 cfm) by the local exhaust system, which consisted of two exhaust terminals, one on each side of the head of the infected manikin. The cabin was ventilated with 180 L/s (381 cfm) of fresh air. Freon was mixed with the air exhaled by the infected manikin...

Assuring robustness to noise in optimal quantum control experiments

International Nuclear Information System (INIS)

Bartelt, A.F.; Roth, M.; Mehendale, M.; Rabitz, H.

2005-01-01

Closed-loop optimal quantum control experiments operate in the inherent presence of laser noise. In many applications, attaining high quality results [i.e., a high signal-to-noise (S/N) ratio for the optimized objective] is as important as producing a high control yield. Enhancement of the S/N ratio will typically be in competition with the mean signal, however, the latter competition can be balanced by biasing the optimization experiments towards higher mean yields while retaining a good S/N ratio. Other strategies can also direct the optimization to reduce the standard deviation of the statistical signal distribution. The ability to enhance the S/N ratio through an optimized choice of the control is demonstrated for two condensed phase model systems: second harmonic generation in a nonlinear optical crystal and stimulated emission pumping in a dye solution

Sound transmission through panels and shells filled with porous material in the presence of external flow

OpenAIRE

Zhou, Jie

2014-01-01

With increasingly tighter regulations on noise exposure during flight, aircraft designers have been compelled to innovate structures that minimise noise transmission into the cabin space. Porous material is widely used as a passive noise control medium because of their light weight, low cost, and broad band sound abatement effectiveness. The present work, inspired by the need to be able to predict noise transmission characteristics for commonly used constructions, incorporates the effect of f...

Products of Ozone-initiated Chemistry during 4-hour Exposures of Human Subjects in a Simulated Aircraft Cabin

DEFF Research Database (Denmark)

Weschler, Charles J.; Wisthaler, Armin; Tamás, Gyöngyi

2006-01-01

Proton-transfer-reaction mass spectrometry (PTR-MS) was used to examine organic compounds in the air of a simulated aircraft cabin under four conditions: low ozone, low air exchange rate; low ozone, high air exchange rate; high ozone, low air exchange rate; high ozone, high air exchange rate....... The results showed large differences in the chemical composition of the cabin air between the low and high ozone conditions. These differences were more pronounced at the low air exchange condition....

Differences in physical workload between military helicopter pilots and cabin crew

NARCIS (Netherlands)

van den Oord, Marieke H. A.; Sluiter, Judith K.; Frings-Dresen, Monique H. W.

2014-01-01

The 1-year prevalence of regular or continuous neck pain in military helicopter pilots of the Dutch Defense Helicopter Command (DHC) is 20%, and physical work exposures have been suggested as risk factors. Pilots and cabin crew perform different tasks when flying helicopters. The aims of the current

PTR-MS Assessment of Photocatalytic and Sorption-Based Purification of Recirculated Cabin Air during Simulated 7-h Flights with High Passenger Density

DEFF Research Database (Denmark)

Wisthaler, Armin; Strøm-Tejsen, Peter; Fang, Lei

2007-01-01

Four different air purification conditions were established in a simulated 3-row 21-seat section of an aircraft cabin: no air purifier; a photocatalytic oxidation unit with an adsorptive prefilter; a second photocatalytic unit with an adsorptive prefil-ter; and a two-stage sorptionbased air filter...... (gas-phase absorption and adsorption). The air purifiers placed in the cabin air recirculation system were commercial prototypes developed for use in aircraft cabin systems. The four conditions were established in balanced order on 4 successive days of each of 4 successive weeks during simulated 7-h...... flights with 17 occupants. Protontransfer reaction mass spectrometry was used to assess organic gas-phase pollutants and the performance of each air purifier. The concentration of most organic pollutants present in aircraft cabin air was effi-ciently reduced by all three units. The photocatalytic units...

Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

DEFF Research Database (Denmark)

Sun, Yuexia; Fang, Lei; Wyon, David P.

2005-01-01

The experiment presented in this report was performed in a simulated aircraft cabin to evalu-ate the air cleaning effects of two air purification devices using Photocatalytic Oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjec-tive human assessments ...

Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

DEFF Research Database (Denmark)

Sun, Yuexia; Fang, Lei; Wyon, David Peter

2008-01-01

The experiment presented in this report was performed in a simulated aircraft cabin to evaluate the air cleaning effects of two air purification devices that used photocatalytic oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjective human assessment...

A Novel Recurrent Neural Network for Manipulator Control With Improved Noise Tolerance.

Science.gov (United States)

Li, Shuai; Wang, Huanqing; Rafique, Muhammad Usman

2017-04-12

In this paper, we propose a novel recurrent neural network to resolve the redundancy of manipulators for efficient kinematic control in the presence of noises in a polynomial type. Leveraging the high-order derivative properties of polynomial noises, a deliberately devised neural network is proposed to eliminate the impact of noises and recover the accurate tracking of desired trajectories in workspace. Rigorous analysis shows that the proposed neural law stabilizes the system dynamics and the position tracking error converges to zero in the presence of noises. Extensive simulations verify the theoretical results. Numerical comparisons show that existing dual neural solutions lose stability when exposed to large constant noises or time-varying noises. In contrast, the proposed approach works well and has a low tracking error comparable to noise-free situations.

Entropy as a measure of the noise extent in a two-level quantum feedback controlled system

Institute of Scientific and Technical Information of China (English)

Wang Tao-Bo; Fang Mao-Fa; Hu Yao-Hua

2007-01-01

By introducing the von Neumann entropy as a measure of the extent of noise, this paper discusses the entropy evolution in a two-level quantum feedback controlled system. The results show that the feedback control can induce the reduction of the degree of noise, and different control schemes exhibit different noise controlling ability, the extent of the reduction also related with the position of the target state on the Bloch sphere. It is shown that the evolution of entropy can provide a real time noise observation and a systematic guideline to make reasonable choice of control strategy.

Effectiveness evaluation of existing noise controls in a deep shaft underground mine.

Science.gov (United States)

Lutz, Eric A; Reed, Rustin J; Turner, Dylan; Littau, Sally R; Lee, Vivien; Hu, Chengcheng

2015-01-01

Noise exposures and hearing loss in the mining industry continue to be a major problem, despite advances in noise control technologies. This study evaluated the effectiveness of engineering, administrative, and personal noise controls using both traditional and in-ear dosimetry by job task, work shift, and five types of earplug. The noise exposures of 22 miners performing deep shaft-sinking tasks were evaluated during 56 rotating shifts in an underground mine. Miners were earplug-insertion trained, earplug fit-tested, and monitored utilizing traditional and in-ear dosimetry. The mean TWA8 noise exposure via traditional dosimetry was 90.1 ± 8.2 dBA, while the mean in-ear TWA8 was 79.6 ± 13.8 dBA. The latter was significantly lower (p < 0.05) than the Mine Safety and Health Administration (MSHA) personal exposure limit (PEL) of 90 dBA. Dosimetry mean TWA8 noise exposures for bench blowing (103.5 ± 0.9 dBA), jumbo drill operation (103.0 ± 0.8 dBA), and mucking tasks (99.6 ± 4.7 dBA) were significantly higher (p < 0.05) than other tasks. For bench blowing, cable pulling, grinding, and jumbo drill operation tasks, the mean in-ear TWA8 was greater than 85 dBA. Those working swing shift had a significantly higher (p < 0.001) mean TWA8 noise exposure (95.4 ± 7.3 dBA) than those working day shift. For percent difference between traditional vs. in-ear dosimetry, there was no significant difference among types of earplug used. Reflective of occupational hearing loss rate trends across the mining industry, this study found that, despite existing engineering and administrative controls, noise exposure levels exceeded regulatory limits, while the addition of personal hearing protection limited excessive exposures.

Two-antenna GNSS Aided-INS Alignment Using Adaptive Control of Filter Noise Covariance

Directory of Open Access Journals (Sweden)

HAO Yushi

2018-04-01

Full Text Available This paper developed a theory of INS fine alignment in order to restrain the divergence of yaw angle,two antennas GNSS aided-INS integrated alignment algorithm was utilized.An attitude error measurement equation was conducted based on the relationship between baseline vectors calculated by two sensors and attitude error.The algorithm was executed by EKF using adaptive control of filter noise covariance.The experimental results showed that stability of the integrated system was improved under the system noise covariance adaptive control mechanism;The measurement noise covariance adaptive control mechanism can reduce the influence of measurement noise and improve the alignment absolute accuracy;Further improvement was achieved under the condition of minim bias of baseline length.The accuracy of roll and pitch was 0.02°,the accuracy of yaw was 0.04°.

Automatic exposure control systems designed to maintain constant image noise: effects on computed tomography dose and noise relative to clinically accepted technique charts.

Science.gov (United States)

Favazza, Christopher P; Yu, Lifeng; Leng, Shuai; Kofler, James M; McCollough, Cynthia H

2015-01-01

To compare computed tomography dose and noise arising from use of an automatic exposure control (AEC) system designed to maintain constant image noise as patient size varies with clinically accepted technique charts and AEC systems designed to vary image noise. A model was developed to describe tube current modulation as a function of patient thickness. Relative dose and noise values were calculated as patient width varied for AEC settings designed to yield constant or variable noise levels and were compared to empirically derived values used by our clinical practice. Phantom experiments were performed in which tube current was measured as a function of thickness using a constant-noise-based AEC system and the results were compared with clinical technique charts. For 12-, 20-, 28-, 44-, and 50-cm patient widths, the requirement of constant noise across patient size yielded relative doses of 5%, 14%, 38%, 260%, and 549% and relative noises of 435%, 267%, 163%, 61%, and 42%, respectively, as compared with our clinically used technique chart settings at each respective width. Experimental measurements showed that a constant noise-based AEC system yielded 175% relative noise for a 30-cm phantom and 206% relative dose for a 40-cm phantom compared with our clinical technique chart. Automatic exposure control systems that prescribe constant noise as patient size varies can yield excessive noise in small patients and excessive dose in obese patients compared with clinically accepted technique charts. Use of noise-level technique charts and tube current limits can mitigate these effects.

Application of acoustically tuned resonators for the improvement of sound insulation in aircraft.

NARCIS (Netherlands)

Hannink, M.H.C.; Vlasma, J.P.; Wijnant, Ysbrand H.; de Boer, Andries

2005-01-01

One of the aims of the EU project FACE (Friendly Aircraft Cabin Environment) is to reduce aircraft interior noise. For modern aircraft flying at cruise conditions, the turbulent boundary layer is the main source for cabin noise. Normally, the turbulent boundary layer causes the trim panels to

Active Control of Inlet Noise on the JT15D Turbofan Engine

Science.gov (United States)

Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

1999-01-01

This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage

Experimental study on brain injury in Beagle dogs caused by adjacent cabin explosion in warship

Directory of Open Access Journals (Sweden)

Yan-teng LI

2017-04-01

Full Text Available Objective 　Through the establishment of adjacent cabin blast injury model of Beagle dog, to investigate the pathophysiological changes in the experimental animals in this scenario, then speculate on the mechanisms of injury. Methods 　Several adjacent cabins were built in the same size with the real warship. Seven Beagle dogs were subjected to injuries from the explosion, from whom one was selected randomly to implant intracranial pressure transducers before blast, the others were tested on the pathophysiological changes after blast. The dogs were mounted on the platform of a cabinet in the adjacent cabin, subjected to injury from 650g bare TNT explosive blast. The transducers recorded the value of space and intracranial shock wave pressure. Following blast treatment, the serum levels of IL -6, IL -8, neuron specific enolase (NSE, brain and chest CT and pathological changes of the brain tissue were observed. Results 　Serum levels of IL-6, IL-8 and NSE were elevated to varying degrees after blast. All of them increased significantly at different time points after blast (P<0.05. Brain and chest CT examinations did not show any significant positive results. Pathological results showed that there was a little necrosis in the brain, some neurons had karyopycnosis, karyolysis or disappearance of the nucleoli, and the cell boundaries were blurred. The blast wave was blocked greatly by the scalp and skull (about 90%, but could still penetrate them and cause brain injuries. Conclusions 　Explosion in the adjacent cabin causes mainly mild traumatic brain injuries. Blast wave can be blocked by the scalp and skull greatly. DOI: 10.11855/j.issn.0577-7402.2017.03.11

Long-term exposure to noise impairs cortical sound processing and attention control.

Science.gov (United States)

Kujala, Teija; Shtyrov, Yury; Winkler, Istvan; Saher, Marieke; Tervaniemi, Mari; Sallinen, Mikael; Teder-Sälejärvi, Wolfgang; Alho, Kimmo; Reinikainen, Kalevi; Näätänen, Risto

2004-11-01

Long-term exposure to noise impairs human health, causing pathological changes in the inner ear as well as other anatomical and physiological deficits. Numerous individuals are daily exposed to excessive noise. However, there is a lack of systematic research on the effects of noise on cortical function. Here we report data showing that long-term exposure to noise has a persistent effect on central auditory processing and leads to concurrent behavioral deficits. We found that speech-sound discrimination was impaired in noise-exposed individuals, as indicated by behavioral responses and the mismatch negativity brain response. Furthermore, irrelevant sounds increased the distractibility of the noise-exposed subjects, which was shown by increased interference in task performance and aberrant brain responses. These results demonstrate that long-term exposure to noise has long-lasting detrimental effects on central auditory processing and attention control.

Design and development of Building energy simulation Software for prefabricated cabin type of industrial building (PCES)

Science.gov (United States)

Zhang, Jun; Li, Ri Yi

2018-06-01

Building energy simulation is an important supporting tool for green building design and building energy consumption assessment, At present, Building energy simulation software can't meet the needs of energy consumption analysis and cabinet level micro environment control design of prefabricated building. thermal physical model of prefabricated building is proposed in this paper, based on the physical model, the energy consumption calculation software of prefabricated cabin building(PCES) is developed. we can achieve building parameter setting, energy consumption simulation and building thermal process and energy consumption analysis by PCES.

Controls in future earth moving machines

NARCIS (Netherlands)

Neve, M. de; Vink, P.; Kanis, H.; Krause, F.

2005-01-01

This seventh chapter of the book 'Advanced cabin design : how to improve comfort and performance by progressive cabin design' explores whether a new way of steering has positive effects. Also controlling the speed of a movement versus the position of a movement is compared. The last 25 years the

Design of aircraft cabin testbed for stress free air travel experiment

NARCIS (Netherlands)

Tan, C.F.; Chen, W.; Rauterberg, G.W.M.

2009-01-01

The paper presents an aircraft cabin testbed that is designed and built for the stress free air travel experiment. The project is funded by European Union in the aim of improving air travel comfort during long haul flight. The testbed is used to test and validate the adaptive system that is capable

Occupant evaluation of 7-hour exposures in a simulated aircraft cabin - Part 1: Optimum balance between fresh air supply and humidity

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Wyon, David Peter; Lagercrantz, Love Per

2005-01-01

Low humidity in the aircraft cabin environment has been identified as a possible cause of symptoms experienced during long flights. A mock-up of a 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber, capable of providing fresh outside air at very...

Effects of Long-Term Speech-in-Noise Training in Air Traffic Controllers and High Frequency Suppression. A Control Group Study.

Science.gov (United States)

Pérez Zaballos, María Teresa; Ramos de Miguel, Ángel; Pérez Plasencia, Daniel; Zaballos González, María Luisa; Ramos Macías, Ángel

2015-12-01

To evaluate 1) if air traffic controllers (ATC) perform better than non-air traffic controllers in an open-set speech-in-noise test because of their experience with radio communications, and 2) if high-frequency information (>8000 Hz) substantially improves speech-in-noise perception across populations. The control group comprised 28 normal-hearing subjects, and the target group comprised 48 ATCs aged between 19 and 55 years who were native Spanish speakers. The hearing -in-noise abilities of the two groups were characterized under two signal conditions: 1) speech tokens and white noise sampled at 44.1 kHz (unfiltered condition) and 2) speech tokens plus white noise, each passed through a 4th order Butterworth filter with 70 and 8000 Hz low and high cutoffs (filtered condition). These tests were performed at signal-to-noise ratios of +5, 0, and -5-dB SNR. The ATCs outperformed the control group in all conditions. The differences were statistically significant in all cases, and the largest difference was observed under the most difficult conditions (-5 dB SNR). Overall, scores were higher when high-frequency components were not suppressed for both groups, although statistically significant differences were not observed for the control group at 0 dB SNR. The results indicate that ATCs are more capable of identifying speech in noise. This may be due to the effect of their training. On the other hand, performance seems to decrease when the high frequency components of speech are removed, regardless of training.

A Comprehensive Assessment of Biologicals Contained Within Commercial Airliner Cabin Air

Science.gov (United States)

LaDuc, Myron T.; Osman, Shariff; Dekas, Anne; Stuecker, Tara; Newcombe, Dave; Piceno, Yvette; Fuhrman, J.; Andersen, Gary; Venkateswaran, Kasthuri; Bearman, Greg

2006-01-01

Both culture-based and culture-independent, biomarker-targeted microbial enumeration and identification technologies were employed to estimate total microbial and viral burden and diversity within the cabin air of commercial airliners. Samples from each of twenty flights spanning three commercial carriers were collected via air-impingement. When the total viable microbial population was estimated by assaying relative concentrations of the universal energy carrier ATP, values ranged from below detection limits (BDL) to 4.1 x 106 cells/cubic m of air. The total viable microbial population was extremely low in both of Airline A (approximately 10% samples) and C (approximately 18% samples) compared to the samples collected aboard flights on Airline A and B (approximately 70% samples). When samples were collected as a function of time over the course of flights, a gradual accumulation of microbes was observed from the time of passenger boarding through mid-flight, followed by a sharp decline in microbial abundance and viability from the initiation of descent through landing. It is concluded in this study that only 10% of the viable microbes of the cabin air were cultivable and suggested a need to employ state-of-the art molecular assay that measures both cultivable and viable-but-non-cultivable microbes. Among the cultivable bacteria, colonies of Acinetobacter sp. were by far the most profuse in Phase I, and Gram-positive bacteria of the genera Staphylococcus and Bacillus were the most abundant during Phase II. The isolation of the human pathogens Acinetobacter johnsonii, A. calcoaceticus, Janibacter melonis, Microbacterium trichotecenolyticum, Massilia timonae, Staphylococcus saprophyticus, Corynebacterium lipophiloflavum is concerning, as these bacteria can cause meningitis, septicemia, and a handful of sometimes fatal diseases and infections. Molecular microbial community analyses exhibited presence of the alpha-, beta-, gamma-, and delta- proteobacteria, as well as

Passenger evaluation of the optimum balance between fresh air supply and humidity from 7-h exposures in a simulated aircraft cabin

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Wyon, David Peter; Lagercrantz, Love Per

2007-01-01

A 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber capable of providing fresh outside air at very low humidity. Maintaining a constant 200 l/s rate of total air supply, i.e. recircu-lated and make-up air, to the cabin, experiments simulating 7...

MD 2485: Active halo control using narrowband and colored noise excitations

CERN Document Server

Garcia Morales, Hector; Kotzian, Gerd; Maclean, Ewen Hamish; Redaelli, Stefano; Valuch, Daniel; Wagner, Joschka; CERN. Geneva. ATS Department

2018-01-01

This MD note summarizes the actions carried out during the MD 2485 on Active halo control using narrowband and colored noise excitations. The goal of the MD was to repeat some promising cases already tested in the past and introduce a new excitation type based on applying a colored noise. Although we were able to repeat some cases using a narrowband excitation, due to a problem with the waveform generator, the colored noise excitation could not be accomplished as expected. In any case, we provide some results that may be useful for future MDs.

The perceptual influence of the cabin acoustics on the reproduced sound of a car audio system

DEFF Research Database (Denmark)

Kaplanis, Neofytos; Bech, Søren; Sakari, Tervo

2015-01-01

-end car audio system was performed for different physical settings of the car's cabin. A novel spatial auralization methodology was then used, and participants were asked to describe verbally the perceived acoustical characteristics of the stimuli. The elicited attributes were then analyzed following...... a previous review [Kaplanis et al., in 55th Int. Conf. Aud. Eng. Soc. (2014)] and possible links to the acoustical properties of the car cabin are discussed. [This study is a part of Marie Curie Network on Dereverberation and Reverberation of Audio, Music, and Speech. EU-FP7 under agreement ITN-GA-2012-316969.]...

Legal and planning framework for the control of noise emissions

International Nuclear Information System (INIS)

Trinick, M.

1992-01-01

An examination is offered of the statutory basis for the control of noise emissions. Principal pieces of legislation and some advisory notes have been produced within appendices. The paper briefly examines the controls in other EC countries before discussing the way in which planning controls relate to the jurisdiction of the court. (author)

Control of noise and structural vibration a MATLAB-based approach

CERN Document Server

Mao, Qibo

2013-01-01

Control of Noise and Structural Vibration presents a MATLAB®-based approach to solving the problems of undesirable noise generation and transmission by structures and of undesirable vibration within structures in response to environmental or operational forces. The fundamentals of acoustics, vibration and coupling between vibrating structures and the sound fields they generate are introduced including a discussion of the finite element method for vibration analysis. Following this, the treatment of sound and vibration control begins, illustrated by example systems such as beams, plates and double plate structures. Sensor and actuator placement is explained as is the idea of modal sensor–actuators. The design of appropriate feedback systems includes consideration of basic stability criteria and robust active structural acoustic control. Single and multi-mode positive position feedback (PPF) control systems are also described in the context of loudspeaker–duct model with non-collocated loudspeaker–microp...

Evaluation of piezoceramic actuators for control of aircraft interior noise

Science.gov (United States)

Silcox, Richard J.; Lefebvre, Sylvie; Metcalf, Vern L.; Beyer, Todd B.; Fuller, Chris R.

1992-01-01

Results of an experiment to evaluate piezoceramic actuators as the control actuator for active control of interior noise in a large-scale fuselage model are presented. Control was demonstrated for tonal excitation using a time domain least mean squares algorithm. A maximum of four actuator channels and six error signals were used. The actuators were employed for control of noise at frequencies where interior cavity modes were the dominant response and for driven acoustic responses where a structure resonance was dominant. Global reductions of 9 to 12 dB were obtained for the cases examined. The most effective configuration of skin-mounted actuators was found to be a pure in-plane forcing function as opposed to a bending excitation. The frame-mounted actuators were found to be equally effective as the skin-mounted actuators. However, both configurations resulted in local regions of unacceptably high vibration response in the structure.

Report on inter-noise 99; Inter-noise 99 sanka hokok

Energy Technology Data Exchange (ETDEWEB)

Koike, H. [Japan Automobile Research Institute Inc., Tsukuba (Japan)

2000-04-01

Inter-Noise (International Congress on Noise Control Engineering) is a society on noise/vibration and the control technology. Inter-Noise 99 was held on December 6, 7 and 8, 1999, at Fort Lauderdale, Florida, the U.S. The theme was Noise Control in the New Millennium. The number of the participants registered was 555 (151 from the U.S., 89 from Japan, 248 from European countries, and 69 from Asian/other countries). Dr. Harold Marshall gave a keynote lecture titled Noise Control by Design in the 21st Century - An Architectural Acoustic Perspective. From a standpoint of architectural acoustics, he stated the perspective, subjects, and course of the technical development pertaining to technologies needed in the 21st century. The papers read are mostly from the following fields: measuring technology, military exercise noise, modeling, forecast and simulation, aerodynamic/underwater sound, etc. In the session on the tire noise where the author read a paper, 14 papers were read. The number of the papers read was more than that in 1998, probably influenced by the tire noise regulation in Europe and Japan. (translated by NEDO)

Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise

Directory of Open Access Journals (Sweden)

Sabine A. Janssen

2011-05-01

Full Text Available In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A‑weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels.

Proximal versus distal control of two-joint planar reaching movements in the presence of neuromuscular noise.

Science.gov (United States)

Nguyen, Hung P; Dingwell, Jonathan B

2012-06-01

Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint

Subjective annoyance caused by indoor low-level and low frequency noise and control method

Institute of Scientific and Technical Information of China (English)

DI Guo-qing; ZHANG Bang-jun; SHANG Qi

2005-01-01

The influence of low-level noise has not been widely noticed. This paper discovered that low-level and low frequency noise(Aweighted equivalent level Leq ＜ 45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium-low frequency noise, the slight increase of medium-high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis.

Engineering the Flow of Liquid Two-Phase Systems by Passive Noise Control

Science.gov (United States)

Zhang, Zeyi; Kong, Tiantian; Zhou, Chunmei; Wang, Liqiu

2018-02-01

We investigate a passive noise-control approach to engineering the two-phase flow in a microfluidic coflow system. The presence or absence of the jet breakup is studied for two immiscible oil phases, in a straight microchannel (referred to as the J device in the main text), an expansion microchannel (the W device) and a microchannel with the expansion-contraction geometry (the S device), respectively. We show that the jet breaks into droplets, in the jetting regime and the dripping regime (also referred to as the widening-jetting regime) for the straight channel and expansion channel, respectively, while a stable long jet does not break for the expansion-contraction geometry. As the inner phase passes the expansion-contraction functional unit, the random noise on the interface is significantly reduced and the hydrodynamic instability is suppressed, for a range of experimental parameters including flow rates, device geometry, liquid viscosity, and interfacial tension. We further present scale-up devices with multiple noise-control units and achieve decimeter-long yet stable jets. Our simple, effective, and robust noise-control approach can benefit microfluidic applications such as microfiber fabrication, interface chemical reaction, and on-chip distance transportation.

Integration and Validation of a Thermal Energy Storage System for Electric Vehicle Cabin Heating

Energy Technology Data Exchange (ETDEWEB)

Wang, Mingyu [MAHLE Behr Troy Inc.; Craig, Timothy [MAHLE Behr Troy Inc.; Wolfe, Edward [MAHLE Behr Troy Inc.; LaClair, Tim J. [ORNL; Gao, Zhiming [ORNL; Levin, Michael [Ford Motor Company; Demitroff, Danrich [Ford Motor Company; Shaikh, Furqan [Ford Motor Company

2017-03-01

It is widely recognized in the automotive industry that, in very cold climatic conditions, the driving range of an Electric Vehicle (EV) can be reduced by 50% or more. In an effort to minimize the EV range penalty, a novel thermal energy storage system has been designed to provide cabin heating in EVs and Plug-in Hybrid Electric Vehicles (PHEVs) by using an advanced phase change material (PCM). This system is known as the Electrical PCM-based Thermal Heating System (ePATHS) [1, 2]. When the EV is connected to the electric grid to charge its traction battery, the ePATHS system is also “charged” with thermal energy. The stored heat is subsequently deployed for cabin comfort heating during driving, for example during commuting to and from work.The ePATHS system, especially the PCM heat exchanger component, has gone through substantial redesign in order to meet functionality and commercialization requirements. The final system development for EV implementation has occurred on a mid-range EV and has been evaluated for its capability to extend the driving range. Both simulated driving in a climatic tunnel and actual road testing have been carried out. The ePATHS has demonstrated its ability to supply the entire cabin heating needs for a round trip commute totaling 46 minutes, including 8 hours of parking, at an ambient temperature of -10°C.

Noise and Sound Control in Open Plan Schools.

Science.gov (United States)

Schellenberg, Ben

This annotated bibliography includes summaries of 19 articles and reports dealing with noise control and acoustical design in school buildings. A brief introduction discusses the need for careful attention to acoustics in any school construction or remodeling project, with particular emphasis on the need for special acoustical measures in an open…

A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator

DEFF Research Database (Denmark)

Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre

The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub-threshol......The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub...

Proceedings of the 2009 spring noise conference : noise awareness : supporting sound partnerships

International Nuclear Information System (INIS)

2009-01-01

This conference provided a forum for industry, government, public, academics and acoustical professionals to discuss innovations in environmental and occupational noise identification, measurement, regulation and control. In addition to raising awareness about expanding noise issues, the conference objectives were to promote responsible industrial development and to identify strategies for reducing workplace noise exposure. The papers focused on research, developments and case studies and highlighted current issues and advancements in technology and software. Speakers from around the world discussed topics ranging from occupational noise issues to low frequency. The 8 sessions were entitled: (1) plenary session, (2) architecture, community planning and public health: effects of noise and noise control, (3) modeling, measurement and technology; (4) noise awareness and education: public, occupational and industrial, (5) regulations and economics: bylaws, legislation and the economics of noise control; (6) student papers, (7) vibration, industrial noise, transportation noise and occupational noise control, and (8) lunch speakers. The conference featured 46 presentations, of which 19 have been catalogued separately for inclusion in this database. refs., tabs., figs.

Control source development for reduction of noise transmitted through a double panel structure

OpenAIRE

Ho, J.

2014-01-01

A double panel structure, which consists of two panels with air in between, is widely adopted in many applications such as aerospace, automotive industries, and buildings due to its low sound transmission at high frequencies, low heat transmission, and low weight. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel’s noise control performance. Applying active structural acoustic control to the panels or active noise control ...

Prevalence of risk factors for breast cancer in German airline cabin crew: a cross-sectional study.

Science.gov (United States)

Winter, Mareen; Blettner, Maria; Zeeb, Hajo

2014-01-01

Many epidemiological studies point to an increased risk of breast cancer among female airline cabin crew. Possible causes include occupational factors (e.g. cosmic radiation exposure, chronodisruption), as well as lifestyle and reproductive factors. To investigate the frequency of various risk factors in German flight attendants which are recognised to be associated with breast cancer. 2708 current and former female cabin crew were randomly selected by a flight attendants' union and mailed a questionnaire; 1311 responded (48% response). Descriptive statistics were used to compare the distribution of breast cancer risk factors with general German population data. On average, cabin crew were 3.0 cm (95% CI 2.7-3.3) taller than the comparison group, while their body mass index was 2.5 kg/m(2) (95% CI 2.4-2.6) lower. We found less use of hormone replacement therapy, but longer average use of oral contraceptives. Nulliparity among respondents aged 45+ was 57% (95% CI 54%-60%) compared to 16%. Average age at first birth was 32.1 years (95% CI 31.7-32.4) vs. 25.5 years. The birth rate was 0.62 (95% CI 0.58-0.67), less than half the population average of 1.34. Alcohol consumption was considerably higher, whereas cabin crew tended to smoke less and performed more physical exercise. We found important differences in terms of anthropometric, gynaecological, reproductive and lifestyle factors. Some of these differences (e.g. higher nulliparity, alcohol consumption, taller size) could contribute to a higher breast cancer risk, whereas others could lead to a reduction (e.g. increased physical exercise, lower BMI, less HRT use).

Multiple-source multiple-harmonic active vibration control of variable section cylindrical structures: A numerical study

Science.gov (United States)

Liu, Jinxin; Chen, Xuefeng; Gao, Jiawei; Zhang, Xingwu

2016-12-01

Air vehicles, space vehicles and underwater vehicles, the cabins of which can be viewed as variable section cylindrical structures, have multiple rotational vibration sources (e.g., engines, propellers, compressors and motors), making the spectrum of noise multiple-harmonic. The suppression of such noise has been a focus of interests in the field of active vibration control (AVC). In this paper, a multiple-source multiple-harmonic (MSMH) active vibration suppression algorithm with feed-forward structure is proposed based on reference amplitude rectification and conjugate gradient method (CGM). An AVC simulation scheme called finite element model in-loop simulation (FEMILS) is also proposed for rapid algorithm verification. Numerical studies of AVC are conducted on a variable section cylindrical structure based on the proposed MSMH algorithm and FEMILS scheme. It can be seen from the numerical studies that: (1) the proposed MSMH algorithm can individually suppress each component of the multiple-harmonic noise with an unified and improved convergence rate; (2) the FEMILS scheme is convenient and straightforward for multiple-source simulations with an acceptable loop time. Moreover, the simulations have similar procedure to real-life control and can be easily extended to physical model platform.

Air Traffic Controllers’ Long-Term Speech-in-Noise Training Effects: A Control Group Study

Science.gov (United States)

Zaballos, María T.P.; Plasencia, Daniel P.; González, María L.Z.; de Miguel, Angel R.; Macías, Ángel R.

2016-01-01

Introduction: Speech perception in noise relies on the capacity of the auditory system to process complex sounds using sensory and cognitive skills. The possibility that these can be trained during adulthood is of special interest in auditory disorders, where speech in noise perception becomes compromised. Air traffic controllers (ATC) are constantly exposed to radio communication, a situation that seems to produce auditory learning. The objective of this study has been to quantify this effect. Subjects and Methods: 19 ATC and 19 normal hearing individuals underwent a speech in noise test with three signal to noise ratios: 5, 0 and −5 dB. Noise and speech were presented through two different loudspeakers in azimuth position. Speech tokes were presented at 65 dB SPL, while white noise files were at 60, 65 and 70 dB respectively. Results: Air traffic controllers outperform the control group in all conditions [P<0.05 in ANOVA and Mann-Whitney U tests]. Group differences were largest in the most difficult condition, SNR=−5 dB. However, no correlation between experience and performance were found for any of the conditions tested. The reason might be that ceiling performance is achieved much faster than the minimum experience time recorded, 5 years, although intrinsic cognitive abilities cannot be disregarded. Discussion: ATC demonstrated enhanced ability to hear speech in challenging listening environments. This study provides evidence that long-term auditory training is indeed useful in achieving better speech-in-noise understanding even in adverse conditions, although good cognitive qualities are likely to be a basic requirement for this training to be effective. Conclusion: Our results show that ATC outperform the control group in all conditions. Thus, this study provides evidence that long-term auditory training is indeed useful in achieving better speech-in-noise understanding even in adverse conditions. PMID:27991470

Active Noise Control Using Modified FsLMS and Hybrid PSOFF Algorithm

Directory of Open Access Journals (Sweden)

Ranjan Walia

2018-04-01

Full Text Available Active noise control is an efficient technique for noise cancellation of the system, which has been defined in this paper with the aid of Modified Filtered-s Least Mean Square (MFsLMS algorithm. The Hybrid Particle Swarm Optimization and Firefly (HPSOFF algorithm are used to identify the stability factor of the MFsLMS algorithm. The computational difficulty of the modified algorithm is reduced when compared with the original Filtered-s Least Mean Square (FsLMS algorithm. The noise sources are removed from the signal and it is compared with the existing FsLMS algorithm. The performance of the system is established with the normalized mean square error for two different types of noises. The proposed method has also been compared with the existing algorithms for the same purposes.

Theoretical investigation of the neutron noise diagnostics of two-dimensional control rod vibrations in a PWR

International Nuclear Information System (INIS)

Pazsit, I.; Analytis, G.T.

1980-01-01

In order to develop a method for monitoring control rod vibrations by neutron noise measurements, the noise induced by two-dimensional vibrations of control elements is investigated. The two-dimensional Green's function relating the small stochastic cross-section fluctuations to the neutron noise is determined for a rectangular slab reactor in the modified one-group theory, and subsequently, the neutron response to two-dimensional vibrating noise sources is investigated. Two possible diagnostical applications are considered: (a) the reconstruction of the mechanical trajectory of the vibrating element by neutron noise measurements, and (b) the possibility of locating the vibrating element in the core. (author)

Advantages for passengers and cabin crew of operating a Gas-Phase Adsorption air purifier in 11-h simulated flights

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Zukowska, Daria; Fang, Lei

2008-01-01

Experiments were carried out in a 3-row, 21-seat section of a simulated aircraft cabin installed in a climate chamber to evaluate the extent to which passengers’ perception of cabin air quality is affected by the operation of a Gas-Phase Adsorption (GPA) purification unit. A total of 68 subjects......, divided into four groups of 17 subjects took part in simulated 11-hour flights. Each group experienced 4 conditions in balanced order, defined by two outside air supply rates (2.4 and 3.3 L/s per person), with and without the GPA purification unit installed in the recirculated air system. During each...... flight the subjects completed questionnaires five times to provide subjective assessments of air quality, cabin environment, intensity of symptoms, and thermal comfort. Additionally, the subjects’ visual acuity, finger temperature, skin dryness and nasal peak flow were measured three times during each...

Application of the remote microphone method to active noise control in a mobile phone.

Science.gov (United States)

Cheer, Jordan; Elliott, Stephen J; Oh, Eunmi; Jeong, Jonghoon

2018-04-01

Mobile phones are used in a variety of situations where environmental noise may interfere with the ability of the near-end user to communicate with the far-end user. To overcome this problem, it might be possible to use active noise control technology to reduce the noise experienced by the near-end user. This paper initially demonstrates that when an active noise control system is used in a practical mobile phone configuration to minimise the noise measured by an error microphone mounted on the mobile phone, the attenuation achieved at the user's ear depends strongly on the position of the source generating the acoustic interference. To help overcome this problem, a remote microphone processing strategy is investigated that estimates the pressure at the user's ear from the pressure measured by the microphone on the mobile phone. Through an experimental implementation, it is demonstrated that this arrangement achieves a significant improvement in the attenuation measured at the ear of the user, compared to the standard active control strategy. The robustness of the active control system to changes in both the interfering sound field and the position of the mobile device relative to the ear of the user is also investigated experimentally.

Comparison between hybrid feedforward-feedback, feedforward, and feedback structures for active noise control of fMRI noise.

Science.gov (United States)

Reddy, Rajiv M; Panahi, Issa M S

2008-01-01

The performance of FIR feedforward, IIR feedforward, FIR feedback, hybrid FIR feedforward--FIR feedback, and hybrid IIR feedforward - FIR feedback structures for active noise control (ANC) are compared for an fMRI noise application. The filtered-input normalized least squares (FxNLMS) algorithm is used to update the coefficients of the adaptive filters in all these structures. Realistic primary and secondary paths of an fMRI bore are used by estimating them on a half cylindrical acrylic bore of 0.76 m (D)x1.52 m (L). Detailed results of the performance of the ANC system are presented in the paper for each of these structures. We find that the IIR feedforward structure produces most of the performance improvement in the hybrid IIR feedforward - FIR feedback structure and adding the feedback structure becomes almost redundant in the case of fMRI noise.

A new laser vibrometry-based 2D selective intensity method for source identification in reverberant fields: part II. Application to an aircraft cabin

International Nuclear Information System (INIS)

Revel, G M; Martarelli, M; Chiariotti, P

2010-01-01

The selective intensity technique is a powerful tool for the localization of acoustic sources and for the identification of the structural contribution to the acoustic emission. In practice, the selective intensity method is based on simultaneous measurements of acoustic intensity, by means of a couple of matched microphones, and structural vibration of the emitting object. In this paper high spatial density multi-point vibration data, acquired by using a scanning laser Doppler vibrometer, have been used for the first time. Therefore, by applying the selective intensity algorithm, the contribution of a large number of structural sources to the acoustic field radiated by the vibrating object can be estimated. The selective intensity represents the distribution of the acoustic monopole sources on the emitting surface, as if each monopole acted separately from the others. This innovative selective intensity approach can be very helpful when the measurement is performed on large panels in highly reverberating environments, such as aircraft cabins. In this case the separation of the direct acoustic field (radiated by the vibrating panels of the fuselage) and the reverberant one is difficult by traditional techniques. The work shown in this paper is the application of part of the results of the European project CREDO (Cabin Noise Reduction by Experimental and Numerical Design Optimization) carried out within the framework of the EU. Therefore the aim of this paper is to illustrate a real application of the method to the interior acoustic characterization of an Alenia Aeronautica ATR42 ground test facility, Alenia Aeronautica being a partner of the CREDO project

Room acoustic analysis of blower unit and noise control plan in the typical steel industry

Directory of Open Access Journals (Sweden)

2013-02-01

Full Text Available Introduction: In the steel industry,air blowers used to supply compressed air are considered as sources of annoying noise. This study aims to acoustics analysis of theairblower workroomand sound source characteristics in order to present noise controlmeasuresinthe steel industry. .Material and Method: Measurement of noiselevel and its frequency analysis was performed usingsound levelmetermodelof CASELLA-Cell.450. Distribution of noise level in the investigated workroom in form of noise map was provided using Surfer software. In addition, acoustic analysis of workroom and control room was performed in view point of soundabsorption andinsulation. Redesignofdoor and window of controlroom and installation of soundabsorbing materialson theceiling of the workroom were proposed and the efficiency of these interventionswasestimated. .Result: The totalsound pressurelevelin the blower workroom was 95.4 dB(L and the dominant frequency was 2000Hz. Sound pressure level inside the room control was 80.1dB(A. The average absorption coefficient and reverberation time in the blower workroom was estimated equal to 0.082 Sab.m2 and 3.9 seconds respectively. These value in control room was 0.04 Sab.m2 and 3/4 seconds respectively. In control room, sound transmission loss between the two parts of the wall dividing was 13.7 dB(A. The average of noise dose in blower operators was 230%. With the installation of sound absorber on ceiling of workroom, average of absorption coefficient can increase to 0.33 Sab.m2 and sound transmission loss of the new designed door and window was estimated equal to 20dB. . Conclusion: The main cause of noise leakage in the control room was insufficient insulation properties of door and windows. By replacing the door and window and installation of sound absorbing on ceiling of workroom, the noise dose can reduce to 49.6%. New Improved door and window of control room can reduce noise dose to 69.65% solely.

Adaptive control of dynamical synchronization on evolving networks with noise disturbances

Science.gov (United States)

Yuan, Wu-Jie; Zhou, Jian-Fang; Sendiña-Nadal, Irene; Boccaletti, Stefano; Wang, Zhen

2018-02-01

In real-world networked systems, the underlying structure is often affected by external and internal unforeseen factors, making its evolution typically inaccessible. An adaptive strategy was introduced for maintaining synchronization on unpredictably evolving networks [Sorrentino and Ott, Phys. Rev. Lett. 100, 114101 (2008), 10.1103/PhysRevLett.100.114101], which yet does not consider the noise disturbances widely existing in networks' environments. We provide here strategies to control dynamical synchronization on slowly and unpredictably evolving networks subjected to noise disturbances which are observed at the node and at the communication channel level. With our strategy, the nodes' coupling strength is adaptively adjusted with the aim of controlling synchronization, and according only to their received signal and noise disturbances. We first provide a theoretical analysis of the control scheme by introducing an error potential function to seek for the minimization of the synchronization error. Then, we show numerical experiments which verify our theoretical results. In particular, it is found that our adaptive strategy is effective even for the case in which the dynamics of the uncontrolled network would be explosive (i.e., the states of all the nodes would diverge to infinity).

Active control of time-varying broadband noise and vibrations using a sliding-window Kalman filter

NARCIS (Netherlands)

van Ophem, S.; Berkhoff, Arthur P.; Sas, P.; Moens, D.; Denayer, H.

2014-01-01

Recently, a multiple-input/multiple-output Kalman filter technique was presented to control time-varying broadband noise and vibrations. By describing the feed-forward broadband active noise control problem in terms of a state estimation problem it was possible to achieve a faster rate of

Implication of Emotional Labor, Cognitive Flexibility, and Relational Energy among Cabin Crew: A Review.

Science.gov (United States)

Baruah, Rithi; Reddy, K Jayasankara

2018-01-01

The primary aim of the civil aviation industry is to provide a secured and comfortable service to their customers and clients. This review concentrates on the cabin crew members, who are the frontline employees of the aviation industry and are salaried to smile. The objective of this review article is to analyze the variables of emotional labor, cognitive flexibility, and relational energy using the biopsychosocial model and identify organizational implications among cabin crew. Online databases such as EBSCOhost, JSTOR, Springerlink, and PubMed were used to gather articles for the review. The authors analyzed 17 articles from 2001 to 2016 and presented a comprehensive review. The review presented an integrative approach and suggested a hypothetical model that can prove to be a signitficant contribution to the avaition industry in particular and to research findings of aviation psychology.

Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise

NARCIS (Netherlands)

Salomons, E.M.; Janssen, S.A.

2011-01-01

In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a

Experimental Model of Contaminant Transport by a Moving Wake Inside an Aircraft Cabin

Science.gov (United States)

Poussou, Stephane; Sojka, Paul; Plesniak, Michael

2008-11-01

The air cabin environment in jetliners is designed to provide comfortable and healthy conditions for passengers. The air ventilation system produces a recirculating pattern designed to minimize secondary flow between seat rows. However, disturbances are frequently introduced by individuals walking along the aisle and may significantly modify air distribution and quality. Spreading of infectious aerosols or biochemical agents presents potential health hazards. A fundamental study has been undertaken to understand the unsteady transport phenomena, to validate numerical simulations and to improve air monitoring systems. A finite moving body is modeled experimentally in a 10:1 scale simplified aircraft cabin equipped with ventilation, at a Reynolds number (based on body height) of the order of 10,000. Measurements of the ventilation and wake velocity fields are obtained using PIV and PLIF. Results indicate that the evolution of the typical downwash behind the body is profoundly perturbed by the ventilation flow. Furthermore, the interaction between wake and ventilation flow significantly alters scalar contaminant migration.

Noise: how can the nuisance be controlled?

Science.gov (United States)

Ollerhead, J B

1973-09-01

Aircraft noise is a major nuisance in residential communities around airports. If the air transport industries are to meet the ever increasing demand for air travel, determined efforts are required now to reduce the burden of noise upon these communities. Significant engine noise reductions have already been achieved in the latest generation of wide-bodied aircraft, and further reductions are being forecast by the engine manufacturers. Regardless of whether there are justifiable grounds for this optimism there are alternative steps to be taken. But the problem is basically an economic rather than a technological one - how much does noise reduction cost and how much can we afford to pay? The various costs of aircraft noise, both monetary and social, are discussed in relation to its effects upon people. Although an economic analysis of the problem is feasible, it is doubtful whether our understanding of the relationships between physical noise levels and human reaction is yet adequate for such purposes. Planning methods for estimating the extent of community noise nuisance are presented, and it is shown that consideration should be given to outlying regions exposed to relatively little aircraft noise.

dc SQUID electronics based on adaptive noise cancellation and a high open-loop gain controller

International Nuclear Information System (INIS)

Seppae, H.

1992-01-01

A low-noise SQUID readout electronics with a high slew rate and an automatic gain control feature has been developed. Flux noise levels of 5x10 -7 Φ 0 /√Hz at 1 kHz and 2x10 -6 Φ 0 /√Hz at 1 Hz have been measured with this readout scheme. The system tolerates sinusoidal disturbances having amplitudes up to 140 Φ 0 at 1 kHz without loosing lock. The electronics utilizes a cooled GaAs FET to control the cancellation of the voltage noise of the room temperature amplifier, a PI 3/2 controller to provide a high open-loop gain at low frequencies, and a square-wave flux and offset voltage modulation to enable automatic control of the noise reduction. The cutoff frequency of the flux-locked-loop is 300 kHz and the feedback gain is more than 130 dB at 10 Hz. (orig.)

Analytical investigation of adaptive control of radiated inlet noise from turbofan engines

Science.gov (United States)

Risi, John D.; Burdisso, Ricardo A.

1994-01-01

An analytical model has been developed to predict the resulting far field radiation from a turbofan engine inlet. A feedforward control algorithm was simulated to predict the controlled far field radiation from the destructive combination of fan noise and secondary control sources. Numerical results were developed for two system configurations, with the resulting controlled far field radiation patterns showing varying degrees of attenuation and spillover. With one axial station of twelve control sources and error sensors with equal relative angular positions, nearly global attenuation is achieved. Shifting the angular position of one error sensor resulted in an increase of spillover to the extreme sidelines. The complex control inputs for each configuration was investigated to identify the structure of the wave pattern created by the control sources, giving an indication of performance of the system configuration. It is deduced that the locations of the error sensors and the control source configuration are equally critical to the operation of the active noise control system.

Effect of human movement on airborne disease transmission in an airplane cabin: study using numerical modeling and quantitative risk analysis.

Science.gov (United States)

Han, Zhuyang; To, Gin Nam Sze; Fu, Sau Chung; Chao, Christopher Yu-Hang; Weng, Wenguo; Huang, Quanyi

2014-08-06

Airborne transmission of respiratory infectious disease in indoor environment (e.g. airplane cabin, conference room, hospital, isolated room and inpatient ward) may cause outbreaks of infectious diseases, which may lead to many infection cases and significantly influences on the public health. This issue has received more and more attentions from academics. This work investigates the influence of human movement on the airborne transmission of respiratory infectious diseases in an airplane cabin by using an accurate human model in numerical simulation and comparing the influences of different human movement behaviors on disease transmission. The Eulerian-Lagrangian approach is adopted to simulate the dispersion and deposition of the expiratory aerosols. The dose-response model is used to assess the infection risks of the occupants. The likelihood analysis is performed as a hypothesis test on the input parameters and different human movement pattern assumptions. An in-flight SARS outbreak case is used for investigation. A moving person with different moving speeds is simulated to represent the movement behaviors. A digital human model was used to represent the detailed profile of the occupants, which was obtained by scanning a real thermal manikin using the 3D laser scanning system. The analysis results indicate that human movement can strengthen the downward transport of the aerosols, significantly reduce the overall deposition and removal rate of the suspended aerosols and increase the average infection risk in the cabin. The likelihood estimation result shows that the risk assessment results better fit the outcome of the outbreak case when the movements of the seated passengers are considered. The intake fraction of the moving person is significantly higher than most of the seated passengers. The infection risk distribution in the airplane cabin highly depends on the movement behaviors of the passengers and the index patient. The walking activities of the crew

BARRIER DESIGN STRATEGIES TO CONTROL NOISE INGRESS INTO DOMESTIC BUILDINGS

Directory of Open Access Journals (Sweden)

Christina E. Mediastika

2003-01-01

Full Text Available Noise source for buildings adjacent to streets is traffic-generated predominantly. Where people are mostly spend their time indoors, it is important for buildings to have screening or blocking to control noise intrusion into living spaces. But this blocking should also permit airflow. This is important for middle to low-cost domestic buildings, which do not employ conditioned ventilation. A common feature of Indonesian buildings, fence, is studied to perform noise barrier. The fence -a barrier to be- should obey three factors: position, dimension, and material. All these three factors were studied to seek compromised design for acoustic performance and natural ventilation purpose. Domestic building situated in the urban area of Yogyakarta was studying to see the most possible design of the barrier to be. There are two calculation methods employed to investigate the proposed design. The study shows that it is possible to gain minimum of 10 dB noise reduction by placing windows within the shadow effect of approximately 1.5 height fence-barrier.

Web-based Traffic Noise Control Support System for Sustainable Transportation

Science.gov (United States)

Fan, Lisa; Dai, Liming; Li, Anson

Traffic noise is considered as one of the major pollutions that will affect our communities in the future. This paper presents a framework of web-based traffic noise control support system (WTNCSS) for a sustainable transportation. WTNCSS is to provide the decision makers, engineers and publics a platform to efficiently access the information, and effectively making decisions related to traffic control. The system is based on a Service Oriented Architecture (SOA) which takes the advantages of the convenience of World Wide Web system with the data format of XML. The whole system is divided into different modules such as the prediction module, ontology-based expert module and dynamic online survey module. Each module of the system provides a distinct information service to the decision support center through the HTTP protocol.

CONTROLLING RISK DUE TO NOISE ON FERRY BOAT

Directory of Open Access Journals (Sweden)

Aleksandar Nikolic

2013-07-01

Full Text Available Environmental and occupational noise is common nuisance that affects the health of employees. Performed health checks of employees engaged by Company “Pomorski Saobraćaj” showed that 5% of examined sailors had hearing loss. The results were a trigger for starting experiment on noise risk assessment with objective to discover possibilities of noise pollution presence, precise significant noise sources and describe solutions for eliminating negative effects. Several measurements on five positions were performed on ferry boat “KAMENARI”, according to EC Physical Agents Directive and Merchant Shipping and Fishing Vessels Regulations 2007. Noise on selected positions exceeded the limit for about 1-5dB. Noise exposure level was 84.5dB. Diesel engine, exhaust system and structural noise were main sources of excessive noise. Experiment shows noise presence as nuisance that affects sailors. Noise presents a serious threat for sailor’s health. It interferes with crew communication and jeopardizes navigation safety. Technical measures, crew health checks and noise monitoring could prevent all negative effects.

Effects of secondary loudspeaker properties on broadband feedforward active duct noise control.

Science.gov (United States)

Chan, Yum-Ji; Huang, Lixi; Lam, James

2013-07-01

Dependence of the performance of feedforward active duct noise control on secondary loudspeaker parameters is investigated. Noise reduction performance can be improved if the force factor of the secondary loudspeaker is higher. For example, broadband noise reduction improvement up to 1.6 dB is predicted by increasing the force factor by 50%. In addition, a secondary loudspeaker with a larger force factor was found to have quicker convergence in the adaptive algorithm in experiment. In simulations, noise reduction is improved in using an adaptive algorithm by using a secondary loudspeaker with a heavier moving mass. It is predicted that an extra broadband noise reduction of more than 7 dB can be gained using an adaptive filter if the force factor, moving mass and coil inductance of a commercially available loudspeaker are doubled. Methods to increase the force factor beyond those of commercially available loudspeakers are proposed.

Assistive technology and passengers with special assistance needs in air transport: contributions to cabin design

Directory of Open Access Journals (Sweden)

Carina Campese

2016-06-01

Full Text Available Abstract There has been significant growth in air transport worldwide, as well as in Brazil. However, studies have emphasized that disabled, obese, and elderly passengers face difficulties when using this means of transport. Among these difficulties, issues related to passengers’ own assistive devices, including damage, loss, or the impossibility of using during the entire flight, stand out. Therefore, the present study aims to understand the trends in assistive technology focusing on cabin design. This research is based upon literature review, interviews with manufacturers and research centers, visits to specialized trade fairs, and patent search. The results revealed a great diversity of assistive products, its trends, and an increase in their use, which affect aircraft cabin design, especially in terms of space, access, and stowage of these devices.

Increase of Investment Appeal of Projects for Noise Control Measures in Urban Environment

Science.gov (United States)

Kolmakov, A. V.; Ignatyeva, V. O.

2017-11-01

The authors analyzed the contemporary noise pollution level in the large cities of the Russian Federation. The article identifies the factors causing the reduction of acoustically comfortable urban territories. It states the task for the increase of investment appeal of the projects aimed at noise control measures adoption.

Quantifying air distribution, ventilation effectiveness and airborne pollutant transport in an aircraft cabin mockup

Science.gov (United States)

Wang, Aijun

The health, safety and comfort of passengers during flight inspired this research into cabin air quality, which is closely related to its airflow distribution, ventilation effectiveness and airborne pollutant transport. The experimental facility is a full-scale aircraft cabin mockup. A volumetric particle tracking velocimetry (VPTV) technique was enhanced by incorporating a self-developed streak recognition algorithm. Two stable recirculation regions, the reverse flows above the seats and the main air jets from the air supply inlets formed the complicated airflow patterns inside the cabin mockup. The primary air flow was parallel to the passenger rows. The small velocity component in the direction of the cabin depth caused less net air exchange between the passenger rows than that parallel to the passenger rows. Different total air supply rate changed the developing behaviors of the main air jets, leading to different local air distribution patterns. Two indices, Local mean age of air and ventilation effectiveness factor (VEF), were measured at five levels of air supply rate and two levels of heating load. Local mean age of air decreased linearly with an increase in the air supply rate, while the VEF remained consistent when the air supply rate varied. The thermal buoyancy force from the thermal plume generated the upside plume flow, opposite to the main jet flow above the boundary seats and thus lowered the local net air exchange. The airborne transport dynamics depends on the distance between the source and the receptors, the relative location of pollutant source, and air supply rate. Exposure risk was significantly reduced with increased distance between source and receptors. Another possible way to decrease the exposure risk was to position the release source close to the exhaust outlets. Increasing the air supply rate could be an effective solution under some emergency situations. The large volume of data regarding the three-dimensional air velocities was

The influence of parametric and external noise in act-and-wait control with delayed feedback.

Science.gov (United States)

Wang, Jiaxing; Kuske, Rachel

2017-11-01

We apply several novel semi-analytic approaches for characterizing and calculating the effects of noise in a system with act-and-wait control. For concrete illustration, we apply these to a canonical balance model for an inverted pendulum to study the combined effect of delay and noise within the act-and-wait setting. While the act-and-wait control facilitates strong stabilization through deadbeat control, a comparison of different models with continuous vs. discrete updating of the control strategy in the active period illustrates how delays combined with the imprecise application of the control can seriously degrade the performance. We give several novel analyses of a generalized act-and-wait control strategy, allowing flexibility in the updating of the control strategy, in order to understand the sensitivities to delays and random fluctuations. In both the deterministic and stochastic settings, we give analytical and semi-analytical results that characterize and quantify the dynamics of the system. These results include the size and shape of stability regions, densities for the critical eigenvalues that capture the rate of reaching the desired stable equilibrium, and amplification factors for sustained fluctuations in the context of external noise. They also provide the dependence of these quantities on the length of the delay and the active period. In particular, we see that the combined influence of delay, parametric error, or external noise and on-off control can qualitatively change the dynamics, thus reducing the robustness of the control strategy. We also capture the dependence on how frequently the control is updated, allowing an interpolation between continuous and frequent updating. In addition to providing insights for these specific models, the methods we propose are generalizable to other settings with noise, delay, and on-off control, where analytical techniques are otherwise severely scarce.

Effects of ozone chemistry and outside air supply on passenger self-evalua-tion of symptoms during 4-hour exposures in a simulated aircraft cabin

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Tamás, Gyöngyi; Myśków, Danuta

2006-01-01

Experiments were carried out in a simulated 21-seat section of an aircraft cabin, installed in a climate chamber, to determine the extent to which cabin air quality and passenger symptoms are affected by ozone chemistry. A total of 30 subjects were exposed to four conditions: two rates of outside...

Listen to the noise: noise is beneficial for cognitive performance in ADHD.

Science.gov (United States)

Söderlund, Göran; Sikström, Sverker; Smart, Andrew

2007-08-01

Noise is typically conceived of as being detrimental to cognitive performance. However, given the mechanism of stochastic resonance, a certain amount of noise can benefit performance. We investigate cognitive performance in noisy environments in relation to a neurocomputational model of attention deficit hyperactivity disorder (ADHD) and dopamine. The Moderate Brain Arousal model (MBA; Sikström & Söderlund, 2007) suggests that dopamine levels modulate how much noise is required for optimal cognitive performance. We experimentally examine how ADHD and control children respond to different encoding conditions, providing different levels of environmental stimulation. Participants carried out self-performed mini tasks (SPT), as a high memory performance task, and a verbal task (VT), as a low memory task. These tasks were performed in the presence, or absence, of auditory white noise. Noise exerted a positive effect on cognitive performance for the ADHD group and deteriorated performance for the control group, indicating that ADHD subjects need more noise than controls for optimal cognitive performance. The positive effect of white noise is explained by the phenomenon of stochastic resonance (SR), i.e., the phenomenon that moderate noise facilitates cognitive performance. The MBA model suggests that noise in the environment, introduces internal noise into the neural system through the perceptual system. This noise induces SR in the neurotransmitter systems and makes this noise beneficial for cognitive performance. In particular, the peak of the SR curve depends on the dopamine level, so that participants with low dopamine levels (ADHD) require more noise for optimal cognitive performance compared to controls.

Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

Science.gov (United States)

Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

1996-01-01

An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

Predicting the Inflow Distortion Tone Noise of the NASA Glenn Advanced Noise Control Fan with a Combined Quadrupole-Dipole Model

Science.gov (United States)

Koch, L. Danielle

2012-01-01

A combined quadrupole-dipole model of fan inflow distortion tone noise has been extended to calculate tone sound power levels generated by obstructions arranged in circumferentially asymmetric locations upstream of a rotor. Trends in calculated sound power level agreed well with measurements from tests conducted in 2007 in the NASA Glenn Advanced Noise Control Fan. Calculated values of sound power levels radiated upstream were demonstrated to be sensitive to the accuracy of the modeled wakes from the cylindrical rods that were placed upstream of the fan to distort the inflow. Results indicate a continued need to obtain accurate aerodynamic predictions and measurements at the fan inlet plane as engineers work towards developing fan inflow distortion tone noise prediction tools.

On the wave induced responses for a high-speed hydrofoil catamaran. Part 1. Cabin connected to hull by spring and its riding comfort in waves; Suichuyokutsuki kosoku sodotei no harochu oto ni tsuite. 1. Dokuritsu kozogata cabin to harochu norigokochi

Energy Technology Data Exchange (ETDEWEB)

Saito, K; Nobukawa, H; Honda, Y [Hiroshima University, Hiroshima (Japan)

1996-04-10

Riding comfort in a cabin of a high-speed hydrofoil catamaran was evaluated by comparing with that in ordinary boats as to acceleration in the vertical direction as one of the responses of the catamaran in waves. First, an equation of motion in waves was introduced, and considerations were given while comparing the result of calculations in regular waves with that of model experiments. Comparison and verification were also performed on response characteristics in irregular waves. A new-type boat, whose cabin is supported with four springs, and provided with hydrofoils in front and rear thereof, was verified to have much less motions of the catamaran bodies and the cabin than in the ordinary boats both in regular and irregular waves. This result was proven by numerical calculations and model experiments. Hydrofoils affect largely the reduction in motions. The correlational data between the results of calculations and experiments are considered sufficient to provide design data, although there are still some points to be improved. These results revealed that the riding comfort of the new-type boat has been improved over that in the ordinary boats. 6 refs., 11 figs., 3 tabs.

Science driven restoration: A candle in a demon haunted world—response to cabin

Science.gov (United States)

Christian P. Giardina; Creighton M. Litton; Jarrod M. Thaxton; Susan Cordell; Lisa J. Hadway; Darren R. Sandquist

2007-01-01

Cabin (2007) asks whether formal science is an effective framework and methodology for designing and implementing ecological restoration programs. He argues that beyond certain ancillary benefits, restoration science has little of practical value to offer the practice of restoration. He goes on to suggest that restoration science most often represents an impediment to...

Minimum power requirement for environmental control of aircraft

International Nuclear Information System (INIS)

Ordonez, Juan Carlos; Bejan, Adrian

2003-01-01

This paper addresses two basic issues in the thermodynamic optimization of environmental control systems (ECS) for aircraft: realistic limits for the minimal power requirement, and design features that facilitate operation at minimal power consumption. Four models are proposed and optimized. In the first, the ECS operates reversibly, the air stream in the cabin is mixed to one temperature, and the cabin experiences heat transfer with the ambient, across its insulation. The cabin temperature is fixed. In the second model, the fixed cabin temperature is assigned to the internal solid surfaces of the cabin, and a thermal resistance separates these surfaces from the air mixed in the cabin. In the third model, the ECS operates irreversibly, based on the bootstrap air cycle. The fourth model combines the ECS features of the third model with the cabin-environment interaction features of the second model. It is shown that in all models the temperature of the air stream that the ECS delivers to the cabin can be optimized for operation at minimal power. The effect of other design parameters and flying conditions is documented. The optimized air delivery temperature is relatively insensitive to the complexity of the model; for example, it is insensitive to the size of the heat exchanger used in the bootstrap air cycle. This study adds to the view that robustness is a characteristic of optimized complex flow systems, and that thermodynamic optimization results can be used for orientation in the pursuit of more complex and realistic designs

Hybrid Feedforward-Feedback Noise Control Using Virtual Sensors

Science.gov (United States)

Bean, Jacob; Fuller, Chris; Schiller, Noah

2016-01-01

Several approaches to active noise control using virtual sensors are evaluated for eventual use in an active headrest. Specifically, adaptive feedforward, feedback, and hybrid control structures are compared. Each controller incorporates the traditional filtered-x least mean squares algorithm. The feedback controller is arranged in an internal model configuration to draw comparisons with standard feedforward control theory results. Simulation and experimental results are presented that illustrate each controllers ability to minimize the pressure at both physical and virtual microphone locations. The remote microphone technique is used to obtain pressure estimates at the virtual locations. It is shown that a hybrid controller offers performance benefits over the traditional feedforward and feedback controllers. Stability issues associated with feedback and hybrid controllers are also addressed. Experimental results show that 15-20 dB reduction in broadband disturbances can be achieved by minimizing the measured pressure, whereas 10-15 dB reduction is obtained when minimizing the estimated pressure at a virtual location.

Semi-automated identification of artefact and noise signals in MEG sensors

International Nuclear Information System (INIS)

Rettich, E.

2006-09-01

Magnetic encephalography (MEG) is a noninvasive method of measuring cerebral activity. It is based on the registration of magnetic fields that are induced by synaptic ion currents as the brain processes information. These magnetic fields are of a very small magnitude, ranging from a few femto Tesla (1 fT = 10 15 T) to several thousand fT (1 pT). This is equivalent to a ten thousandth to a billionth of the Earth's magnetic field. When applied with a time resolution in the range of milliseconds this technique permits research on time-critical neurophysiological processes. A meaningful analysis of MEG data presupposes that signals have been measured at low noise levels. This in turn requires magnetic shielding, normally in the form of a shielded cabin, and low-noise detectors. Data input from high-noise channels impairs the result of the measurement, possibly rendering it useless. To prevent this it is necessary to identify high-noise channels and remove them from the measurement data. At Juelich Research Center, like at most MEG laboratories, this is done by visual inspection. However, being dependent on the individual observer, this method does not yield objective results. Furthermore, visual inspection presupposes a high degree of experience and is time-consuming. This situation could be significantly improved by automated identification of high-noise channels. The purpose of the present study was to develop an algorithm that analyses measurement signals in a given time and frequency interval on the basis of statistical traits. Using a suitably designed user interface this permits searching MEG data for high-noise channel data below or above statistical threshold values on the basis of predetermined decision criteria. The identified high-noise channels are then output in a selection list, and the measurement data and results of the statistical analysis are displayed. This information enables the user to make changes and decide which high-noise channels to extract

Noise pollution resources compendium

Science.gov (United States)

1973-01-01

Abstracts of reports concerning noise pollution are presented. The abstracts are grouped in the following areas of activity: (1) sources of noise, (2) noise detection and measurement, (3) noise abatement and control, (4) physical effects of noise and (5) social effects of noise.

NOISE CONTROL OF VEHICLE DRIVE SYSTEMS

Directory of Open Access Journals (Sweden)

Ulrich Gabbert

2017-08-01

Full Text Available The paper presents an overall simulation approach to control the noise emission of car engines at a very early stage of the design process where no real prototypes are available. The suggested approach combines different physical models and couples different software tools such as multi-body analysis, fluid dynamics, structural mechanics, magneto-electrodynamics, thermodynamics, acoustics and control as well. The general overall simulation methodology is presented first. Then, this methodology is applied to a combustion engine in order to improve its acoustical behavior by passive means, such as changing the stiffness and the use of damping materials to build acoustic and thermal encapsulations. The active control by applying piezoelectric patch actuators at the oil sump as the noisiest part of the engine is discussed as well. The sound emission is evaluated by hearing tests and a mathematical prediction model of the human perception. Finally, it is shown that the presented approach can be extended to electric engines, which is demonstrated at a newly developed electric wheel hub motor.

International Space Station Crew Quarters Ventilation and Acoustic Design Implementation

Science.gov (United States)

Broyan, James L., Jr.; Cady, Scott M; Welsh, David A.

2010-01-01

The International Space Station (ISS) United States Operational Segment has four permanent rack sized ISS Crew Quarters (CQs) providing a private crew member space. The CQs use Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air-from the ISS Common Cabin Air Assembly (CCAA) or the ISS fluid cooling loop. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crew member's head position and reduce acoustic exposure. The CQ ventilation ducts are conduits to the louder Node 2 cabin aisle way which required significant acoustic mitigation controls. The CQ interior needs to be below noise criteria curve 40 (NC-40). The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. Each CQ required 13% of its total volume and approximately 6% of its total mass to reduce acoustic noise. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

Fault-tolerant controlled quantum secure direct communication over a collective quantum noise channel

International Nuclear Information System (INIS)

Yang, Chun-Wei; Hwang, Tzonelih; Tsai, Chia-Wei

2014-01-01

This work proposes controlled quantum secure direct communication (CQSDC) over an ideal channel. Based on the proposed CQSDC, two fault-tolerant CQSDC protocols that are robust under two kinds of collective noises, collective-dephasing noise and collective-rotation noise, respectively, are constructed. Due to the use of quantum entanglement of the Bell state (or logical Bell state) as well as dense coding, the proposed protocols provide easier implementation as well as better qubit efficiency than other CQSDC protocols. Furthermore, the proposed protocols are also free from correlation-elicitation attack and other well-known attacks. (paper)

Spacecraft cabin environment effects on the growth and behavior of Chlorella vulgaris for life support applications

Science.gov (United States)

Niederwieser, Tobias; Kociolek, Patrick; Klaus, David

2018-02-01

An Environmental Control and Life Support System (ECLSS) is necessary for humans to survive in the hostile environment of space. As future missions move beyond Earth orbit for extended durations, reclaiming human metabolic waste streams for recycled use becomes increasingly important. Historically, these functions have been accomplished using a variety of physical and chemical processes with limited recycling capabilities. In contrast, biological systems can also be incorporated into a spacecraft to essentially mimic the balance of photosynthesis and respiration that occurs in Earth's ecosystem, along with increasing the reuse of biomass throughout the food chain. In particular, algal photobioreactors that use Chlorella vulgaris have been identified as potential multifunctional components for use as part of such a bioregenerative life support system (BLSS). However, a connection between the biological research examining C. vulgaris behavior and the engineered spacecraft cabin environmental conditions has not yet been thoroughly established. This review article characterizes the ranges of prior and expected cabin parameters (e.g. temperature, lighting, carbon dioxide, pH, oxygen, pressure, growth media, contamination, gravity, and radiation) and reviews algal metabolic response (e.g. growth rate, composition, carbon dioxide fixation rates, and oxygen evolution rates) to changes in those parameters that have been reported in prior space research and from related Earth-based experimental observations. Based on our findings, it appears that C. vulgaris offers many promising advantages for use in a BLSS. Typical atmospheric conditions found in spacecraft such as elevated carbon dioxide levels are, in fact, beneficial for algal cultivation. Other spacecraft cabin parameters, however, introduce unique environmental factors, such as reduced total pressure with elevated oxygen concentration, increased radiation, and altered gravity, whose effects on the biological responses

Noise, buildings and people

Energy Technology Data Exchange (ETDEWEB)

Croome, D J

1977-01-01

This book covers the physics of acoustics necessary to understand the analytical aspects of acoustical design and noise control in buildings. The major part is devoted to the problems of noise and man, and other chapters cover features of noise control in and around buildings. In an introduction, building environmental engineering is dealth with in general terms of architecture, creativity, systms design, etc. Aspects of the acoustical environment, noise sources in buildings, control of airborne and structure-borne noise and acoustical design techniques are covered in Part II. Items include: comfort, physiological response to noise and vibrations, noise criteria, human performance, speech communication, landscaped offices, sound generation by air-conditioning and heating equipment, building structure and noise attenuation, acoustical design. Part III gives some fundamentals of acoustics; mechanical vibration, wave motion, propagation of sound, structure-borne sound, behavior of sound in rooms, transmission of sound through structure. References include lists of British standards and booklets on health and safety at work.

Possibilities to employ noise analysis techniques in controlling nuclear power stations

International Nuclear Information System (INIS)

Alfonso Pallares, C.; Iglesias Ferrer, R.; Sarabia Molina, I.

1998-01-01

This work shows basic requirements the authors think must be complied with by monitoring systems for operational surveillance based on noise analysis techniques that in turn can be employed in the regulatory control

Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization

Science.gov (United States)

Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

2014-01-01

This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.

77 FR 72998 - Policy Statement on Occupational Safety and Health Standards for Aircraft Cabin Crewmembers

Science.gov (United States)

2012-12-07

... [Docket No.: FAA-2012-0953] Policy Statement on Occupational Safety and Health Standards for Aircraft... regarding the regulation of some occupational safety and health conditions affecting cabin crewmembers on aircraft by the Occupational Safety and Health Administration (OSHA). This policy statement will enhance...

Psycho-acoustic evaluation of the indoor noise in cabins of a naval vessel using a back-propagation neural network algorithm

OpenAIRE

Han, Hyung-Suk

2012-01-01

The indoor noise of a ship is usually determined using the A-weighted sound pressure level. However, in order to better understand this phenomenon, evaluation parameters that more accurately reflect the human sense of hearing are required. To find the level of the satisfaction index of the noise inside a naval vessel such as “Loudness” and “Annoyance”, psycho-acoustic evaluation of various sound recordings from the naval vessel was performed in a laboratory. The objective of this paper is to ...

Development of automatic air intake door control system for exhaust gas. Prevention of contaminated air by controlling A/C air intake door; Haiki gas taio auto naigaiki system no kaihatsu. Eakon suikomiguchi seigyo ni yoru haiki gas no shashitsunai eno shinnyu boshi

Energy Technology Data Exchange (ETDEWEB)

Honda, Y; Samukawa, K [Denso Corp., Aichi (Japan)

1997-10-01

Thermal comfort in the cabin of vehicle is upgraded by developing the climate control system Passengers must control the intake door of air conditioner to reduce entering Exhaust Gas into the cabin. This paper is concerned with development the automatic intake door control system to acquire high comfort performance of passengers. 8 figs., 1 tab.

Evaluation of retrofit crankcase ventilation controls and diesel oxidation catalysts for reducing air pollution in school buses

Science.gov (United States)

Trenbath, Kim; Hannigan, Michael P.; Milford, Jana B.

2009-12-01

This study evaluates the effect of retrofit closed crankcase ventilation filters (CCFs) and diesel oxidation catalysts (DOCs) on the in-cabin air quality in transit-style diesel school buses. In-cabin pollution levels were measured on three buses from the Pueblo, CO District 70 fleet. Monitoring was conducted while buses were driven along their regular routes, with each bus tested three times before and three times after installation of control devices. Ultrafine number concentrations in the school bus cabins were 33-41% lower, on average, after the control devices were installed. Mean mass concentrations of particulate matter less than 2.5 μm in diameter (PM2.5) were 56% lower, organic carbon (OC) 41% lower, elemental carbon (EC) 85% lower, and formaldehyde 32% lower after control devices were installed. While carbon monoxide concentrations were low in all tests, mean concentrations were higher after control devices were installed than in pre-retrofit tests. Reductions in number, OC, and formaldehyde concentrations were statistically significant, but reductions in PM2.5 mass were not. Even with control devices installed, during some runs PM2.5 and OC concentrations in the bus cabins were elevated compared to ambient concentrations observed in the area. OC concentrations inside the bus cabins ranged from 22 to 58 μg m -3 before and 13 to 33 μg m -3 after control devices were installed. OC concentrations were correlated with particle-bound organic tracers for lubricating oil emissions (hopanes) and diesel fuel and tailpipe emissions (polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons). Mean concentrations of hopanes, PAH, and aliphatic hydrocarbons were lower by 37, 50, and 43%, respectively, after the control devices were installed, suggesting that both CCFs and DOCs were effective at reducing in-cabin OC concentrations.

The influence of ozone on self-evaluation of symptoms in a simulated aircraft cabin

DEFF Research Database (Denmark)

Strøm-Tejsen, Peter; Weschler, Charles J.; Wargocki, Pawel

2008-01-01

Simulated 4-h flights were carried out in a realistic model of a three-row, 21-seat section of an aircraft cabin that was reconstructed inside a climate chamber. Twenty-nine female subjects, age 19-27 years, were split into two groups; each group was exposed to four conditions: two levels of ozone (...

Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

Science.gov (United States)

Ho, Jen-Hsuan; Berkhoff, Arthur

2014-03-01

This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of two panels with air in between and offers the advantages of low sound transmission at high frequencies, low heat transmission, and low weight. The double panel structure is widely used, such as in the aerospace and automotive industries. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel's noise control performance. Applying active structural acoustic control to the panels or active noise control to the cavity has been discussed in many papers. In this paper, the resonances of the panels and the cavity are considered simultaneously to further reduce the transmitted noise through an existing double panel structure. A structural-acoustic coupled model is developed to investigate and compare various structural control and cavity control methods. Numerical analysis and real-time control results show that structural control should be applied to both panels. Three types of cavity control sources are presented and compared. The results indicate that the largest noise reduction is obtained with cavity control by loudspeakers modified to operate as incident pressure sources.

Scanning probe microscope simulator for the assessment of noise in scanning probe microscopy controllers

International Nuclear Information System (INIS)

Wutscher, T.; Niebauer, J.; Giessibl, F. J.

2013-01-01

We present an electronic circuit that allows to calibrate and troubleshoot scanning probe microscopy (SPM) controllers with respect to their noise performance. The control signal in an SPM is typically highly nonlinear—the tunneling current in scanning tunneling microscopy (STM) varies exponentially with distance. The exponential current-versus-voltage characteristics of diodes allow to model the current dependence in STM. Additional inputs allow to simulate the effects of external perturbations and the reactions of the control electronics. We characterized the noise performance of the feedback controller using the apparent topography roughness of recorded images. For a comparison of different STM controllers, an optimal gain parameter was determined by exploring settling times through a rectangular perturbation signal. We used the circuit to directly compare the performance of two types of SPM controllers used in our laboratory

Estimated radiation exposure of German commercial airline cabin crew in the years 1960-2003 modeled using dose registry data for 2004-2015.

Science.gov (United States)

Wollschläger, Daniel; Hammer, Gaël Paul; Schafft, Thomas; Dreger, Steffen; Blettner, Maria; Zeeb, Hajo

2018-05-01

Exposure to ionizing radiation of cosmic origin is an occupational risk factor in commercial aircrew. In a historic cohort of 26,774 German aircrew, radiation exposure was previously estimated only for cockpit crew using a job-exposure matrix (JEM). Here, a new method for retrospectively estimating cabin crew dose is developed. The German Federal Radiation Registry (SSR) documents individual monthly effective doses for all aircrew. SSR-provided doses on 12,941 aircrew from 2004 to 2015 were used to model cabin crew dose as a function of age, sex, job category, solar activity, and male pilots' dose; the mean annual effective dose was 2.25 mSv (range 0.01-6.39 mSv). In addition to an inverse association with solar activity, exposure followed age- and sex-dependent patterns related to individual career development and life phases. JEM-derived annual cockpit crew doses agreed with SSR-provided doses for 2004 (correlation 0.90, 0.40 mSv root mean squared error), while the estimated average annual effective dose for cabin crew had a prediction error of 0.16 mSv, equaling 7.2% of average annual dose. Past average annual cabin crew dose can be modeled by exploiting systematic external influences as well as individual behavioral determinants of radiation exposure, thereby enabling future dose-response analyses of the full aircrew cohort including measurement error information.

Application of Circulation Control Technology to Airframe Noise Reduction

Science.gov (United States)

Ahuja, K. K.; Sankar, L. N.; Englar, R. J.; Munro, Scott E.; Li, Yi; Gaeta, R. J.

2003-01-01

This report is a summary of the work performed by Georgia Tech Research Institute (GTRI) under NASA Langley Grant NAG-1-2146, which was awarded as a part of NASA's Breakthrough Innovative Technologies (BIT) initiative. This was a three-year program, with a one-year no-cost extension. Each year's study has been an integrated effort consisting of computational fluid dynamics, experimental aerodynamics, and detailed noise and flow measurements. Year I effort examined the feasibility of reducing airframe noise by replacing the conventional wing systems with a Circulation Control Wing (CCW), where steady blowing was used through the trailing edge of the wing over a Coanda surface. It was shown that the wing lift increases with CCW blowing and indeed for the same lift, a CCW wing was shown to produce less noise. Year 2 effort dealt with a similar study on the role of pulsed blowing on airframe noise. The main objective of this portion of the study was to assess whether pulse blowing from the trailing edge of a CCW resulted in more, less, or the same amount of radiated noise to the farfield. Results show that a reduction in farfield noise of up to 5 dB is measured when pulse flow is compared with steady flow for an equivalent lift configuration. This reduction is in the spectral region associated with the trailing edge jet noise. This result is due to the unique advantage that pulsed flow has over steady flow. For a range of frequencies, more lift is experienced with the same mass flow as the steady case. Thus, for an equivalent lift and slot height, the pulsed system can operate at lower jet velocities, and hence lower jet noise. The computational analysis showed that for a given time-averaged mass flow rate, pulsed jets give a higher value of C(sub l) and a higher L/D than equivalent steady jets. This benefit is attributable to higher instantaneous jet velocities, and higher instantaneous C(sub mu) values for the pulsed jet. Pulsed jet benefits increase at higher

Market Potential Study for Standing Cabin Concept for Domestic Low-Cost Commercial Airlines in Malaysia

Science.gov (United States)

Romli, Fairuz I.; Dasuki, Norhafizah; Yazdi Harmin, Mohammad

2016-02-01

An affordable air transportation has become the operational aim of many airlines these days. This is to cater the growing air travel demands from people of different social and economic status. One of the revolutionary proposals to reduce the operational costs, hence the flight ticket price, is by introducing the so-called standing cabin concept. This concept involves transporting passengers during the entire flight in their standing position with a proper support of a vertical seat. As can be expected with many new inventions, despite its clear advantages, the concept has been met with mixed reactions from the public. This study intends to establish whether the standing cabin concept has a market potential to be implemented for domestic flights in Malaysia. The public perception is determined from collected data through a survey done at two major local low-cost airport terminals. It can be concluded from the results that the concept has a good market potential for application on flights with duration of less than two hours.

Spreadsheet tool for estimating noise reduction costs

International Nuclear Information System (INIS)

Frank, L.; Senden, V.; Leszczynski, Y.

2009-01-01

The Northeast Capital Industrial Association (NCIA) represents industry in Alberta's industrial heartland. The organization is in the process of developing a regional noise management plan (RNMP) for their member companies. The RNMP includes the development of a noise reduction cost spreadsheet tool to conduct reviews of practical noise control treatments available for individual plant equipment, inclusive of ranges of noise attenuation achievable, which produces a budgetary prediction of the installed cost of practical noise control treatments. This paper discussed the noise reduction cost spreadsheet tool, with particular reference to noise control best practices approaches and spreadsheet tool development such as prerequisite, assembling data required, approach, and unit pricing database. Use and optimization of the noise reduction cost spreadsheet tool was also discussed. It was concluded that the noise reduction cost spreadsheet tool is an easy interactive tool to estimate implementation costs related to different strategies and options of noise control mitigating measures and was very helpful in gaining insight for noise control planning purposes. 2 tabs.

Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Gaponenko, I., E-mail: iaroslav.gaponenko@unige.ch; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P. [DQMP, University of Geneva, 24 Quai E. Ansermet, 1211 Geneva 4 (Switzerland)

2016-06-15

We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

Science.gov (United States)

Gaponenko, I.; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P.

2016-06-01

We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

International Nuclear Information System (INIS)

Gaponenko, I.; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P.

2016-01-01

We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

Effects of Noise and Time Delay Upon Active Control of Combustion Instabilities

National Research Council Canada - National Science Library

Zinn, Ben

2001-01-01

To improve the performance of practical active control system (ACS) for unstable combustors, the effects of system noise and ACS time delay upon combustion instabilities and the ACS performance were studied...

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation

Energy Technology Data Exchange (ETDEWEB)

Huang, Yong, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn; Tao, Gang, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, 200 XiaoLingwei Street, Nanjing 210094 (China)

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation.

Science.gov (United States)

Huang, Yong; Tao, Gang

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

Experimental investigation of airborne contaminant transport by a human wake moving in a ventilated aircraft cabin

Science.gov (United States)

Poussou, Stephane B.

The air ventilation system in jetliners provides a comfortable and healthy environment for passengers. Unfortunately, the increase in global air traffic has amplified the risks presented by infectious aerosols or noxious material released during flight. Inside the cabin, air typically flows continuously from overhead outlets into sidewall exhausts in a circular pattern that minimizes secondary flow between adjacent seat rows. However, disturbances frequently introduced by individuals walking along an aisle may alter air distribution, and contribute to spreading of contaminants. Numerical simulation of these convoluted transient flow phenomena is difficult and complex, and experimental assessment of contaminant distribution in real cabins often impractical. A fundamental experimental study was undertaken to examine the transport phenomena, to validate computations and to improve air monitoring systems. A finite moving body was modeled in a 10:1 scale simplified aircraft cabin equipped with ventilation, at a Reynolds number (based on body diameter) of the order of 10,000. An experimental facility was designed and constructed to permit measurements of the ventilation and wake velocity fields using particle image velocimetry (PIV). Contaminant migration was imaged using the planar laser induced fluorescence (PLIF) technique. The effect of ventilation was estimated by comparison with a companion baseline study. Results indicate that the evolution of a downwash predominant behind finite bodies of small aspect ratio is profoundly perturbed by the ventilation flow. The reorganization of vortical structures in the near-wake leads to a shorter longitudinal recirculation region. Furthermore, mixing in the wake is modified and contaminant is observed to convect to higher vertical locations corresponding to seated passenger breathing level.

Spin noise amplification and giant noise in optical microcavity

Energy Technology Data Exchange (ETDEWEB)

Ryzhov, I. I.; Poltavtsev, S. V.; Kozlov, G. G.; Zapasskii, V. S. [Spin-Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg (Russian Federation); Kavokin, A. V. [Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Spin-Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg (Russian Federation); Lagoudakis, P. V. [Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

2015-06-14

When studying the spin-noise-induced fluctuations of Kerr rotation in a quantum-well microcavity, we have found a dramatic increase of the noise signal (by more than two orders of magnitude) in the vicinity of anti-crossing of the polariton branches. The effect is explained by nonlinear optical instability of the microcavity giving rise to the light-power-controlled amplification of the polarization noise signal. In the framework of the developed model of built-in amplifier, we also interpret the nontrivial spectral and intensity-related properties of the observed noise signal below the region of anti-crossing of polariton branches. The discovered effect of optically controllable amplification of broadband polarization signals in microcavities in the regime of optical instability may be of interest for detecting weak oscillations of optical anisotropy in fundamental research and for other applications in optical information processing.

Classical noise, quantum noise and secure communication

International Nuclear Information System (INIS)

Tannous, C; Langlois, J

2016-01-01

Secure communication based on message encryption might be performed by combining the message with controlled noise (called pseudo-noise) as performed in spread-spectrum communication used presently in Wi-Fi and smartphone telecommunication systems. Quantum communication based on entanglement is another route for securing communications as demonstrated by several important experiments described in this work. The central role played by the photon in unifying the description of classical and quantum noise as major ingredients of secure communication systems is highlighted and described on the basis of the classical and quantum fluctuation dissipation theorems. (review)

Noise-induced hearing loss and associated factors among vector control workers in a Malaysian state.

Science.gov (United States)

Masilamani, Retneswari; Rasib, Abdul; Darus, Azlan; Ting, Anselm Su

2014-11-01

This study aims to determine the prevalence and associated factors of noise-induced hearing loss (NIHL) among vector control workers in the state of Negeri Sembilan, Malaysia. This was an analytical cross-sectional study conducted on 181 vector control workers who were working in district health offices in a state in Malaysia. Data were collected using a self-administered questionnaire and audiometry. Prevalence of NIHL was 26% among this group of workers. NIHL was significantly associated with the age-group of 40 years and older, length of service of 10 or more years, current occupational noise exposure, listening to loud music, history of firearms use, and history of mumps/measles infection. Following logistic regression, age of more than 40 years and noise exposure in current occupation were associated with NIHL with an odds ratio of 3.45 (95% confidence interval = 1.68-7.07) and 6.87 (95% confidence interval = 1.54-30.69), respectively, among this group of vector control workers. © 2012 APJPH.

Developing noise control strategies for entire railway networks

Science.gov (United States)

Oertli, Jakob

2006-06-01

The EU Environmental Noise Directive (2002/49) requires member states to deliver noise maps to the commission by 2007 and action plans by 2008 both for agglomerations as well as for major roads, railways and airports. Noise mitigation projects resulting from action plans are usually very expensive and therefore may threaten the economic viability of the railways in the current harsh competitive transport market, thus hindering sustainable transport policies. It is therefore of vital interest that the action plans and the resulting projects are designed in the most cost-effective way possible. The EU and Union of Railways (UIC) sponsored project Strategies and Tools to Assess and Implement noise Reducing measures for Railway Systems (STAIRRS) recognized this need and developed a tool, with which such optimal solutions can be obtained for entire railway networks. Since data collection is the most expensive part of the analysis, noise mapping data is ideally collected in such a way that it can be used for the calculation of the different scenarios, from which the most cost-effective action plans are chosen. The paper shows how the STAIRRS tool is used for this purpose and how cost-effectiveness considerations have led to optimal railway noise mitigation strategies in Switzerland and have given a basis for noise related decision making in Luxembourg.

Interactive aircraft cabin testbed for stress-free air travel system experiment: an innovative concurrent design approach

NARCIS (Netherlands)

Tan, C.F.; Chen, W.; Rauterberg, G.W.M.

2009-01-01

In this paper, a study of the concurrent engineering design for the environmental friendly low cost aircraft cabin simulator is presented. The study describes the used of concurrent design technique in the design activity. The simulator is a testbed that was designed and built for research on

L4-L5 compression and anterior/posterior joint shear forces in cabin attendants during the initial push/pull actions of airplane meal carts

DEFF Research Database (Denmark)

Sandfeld, Jesper; Rosgaard, Christian; Jensen, Bente Rona

2014-01-01

The aim of the present study was to assess the acute low back load of cabin attendants during cart handling and to identify working situations which present the highest strain on the worker. In a setup, 17 cabin attendants (ten females and seven males) pushed, pulled and turned a 20kg standard meal...... was used to calculate the acute L4-L5 load. No working situations created loads greater than the accepted values for single exertions, however compression and anterior/posterior shear forces during pulling and turning were much higher when compared with pushing. There were significant effects of handling...... the cart on different floor types, at the varying inclinations and with different cart weights. Additionally, when external forces were reduced, the cabin attendants did not decrease push/pull force proportionally and thus the L4-L5 load did not decrease as much as expected....

The effect of low ceiling on the external combustion of the cabin fire

Science.gov (United States)

Su, Shichuan; Chen, Changyun; Wang, Liang; Wei, Chengyin; Cui, Haibing; Guo, Chengyu

2018-06-01

External combustion is a phenomenon where the flame flares out of the window and burns outside. Because of the particularity of the ship's cabin structure, there is a great danger in the external combustion. In this paper, the numerical calculation and analysis of three kinds of low ceiling ship cabin fire are analyzed based on the large eddy numerical simulation technique. Through the analysis of temperature, flue gas velocity, heat flux density and so on, the external combustion phenomenon of fire development is calculated. The results show that when external combustion occurs, the amount of fuel escaping decreases with the roof height. The temperature above the window increases with the height of the ceiling. The heat flux density in the external combustion flame is mainly provided by radiation, and convection is only a small part; In the plume area there is a time period, in this time period, the convective heat flux density is greater than the radiation heat flux, this time with the ceiling height increases. No matter which ceiling height, the external combustion will seriously damage the structure of the ship after a certain period of time. The velocity distribution of the three roof is similar, but with the height of the ceiling, the area size is also increasing.

Cyclic pitch for the control of wind turbine noise amplitude modulation

DEFF Research Database (Denmark)

Bertagnolio, Franck; Aagaard Madsen, Helge; Fischer, Andreas

2014-01-01

Using experimental data acquired during a wind turbine measurement campaign, it is shown that amplitude modulation of aerodynamic noise can be generated by the rotating blades in conjunction with the atmospheric wind shear. As an attempt to alleviate this phenomenon, a control strategy is designed...... if such a strategy is to be implemented on an actual wind turbine, though at the expense of an increased wear and tear of the pitch control system....

Visual signal detection in structured backgrounds. II. Effects of contrast gain control, background variations, and white noise

Science.gov (United States)

Eckstein, M. P.; Ahumada, A. J. Jr; Watson, A. B.

1997-01-01

Studies of visual detection of a signal superimposed on one of two identical backgrounds show performance degradation when the background has high contrast and is similar in spatial frequency and/or orientation to the signal. To account for this finding, models include a contrast gain control mechanism that pools activity across spatial frequency, orientation and space to inhibit (divisively) the response of the receptor sensitive to the signal. In tasks in which the observer has to detect a known signal added to one of M different backgrounds grounds due to added visual noise, the main sources of degradation are the stochastic noise in the image and the suboptimal visual processing. We investigate how these two sources of degradation (contrast gain control and variations in the background) interact in a task in which the signal is embedded in one of M locations in a complex spatially varying background (structured background). We use backgrounds extracted from patient digital medical images. To isolate effects of the fixed deterministic background (the contrast gain control) from the effects of the background variations, we conduct detection experiments with three different background conditions: (1) uniform background, (2) a repeated sample of structured background, and (3) different samples of structured background. Results show that human visual detection degrades from the uniform background condition to the repeated background condition and degrades even further in the different backgrounds condition. These results suggest that both the contrast gain control mechanism and the background random variations degrade human performance in detection of a signal in a complex, spatially varying background. A filter model and added white noise are used to generate estimates of sampling efficiencies, an equivalent internal noise, an equivalent contrast-gain-control-induced noise, and an equivalent noise due to the variations in the structured background.

A separation theorem for the stochastic sampled-data LQG problem. [control of continuous linear plant disturbed by white noise

Science.gov (United States)

Halyo, N.; Caglayan, A. K.

1976-01-01

This paper considers the control of a continuous linear plant disturbed by white plant noise when the control is constrained to be a piecewise constant function of time; i.e. a stochastic sampled-data system. The cost function is the integral of quadratic error terms in the state and control, thus penalizing errors at every instant of time while the plant noise disturbs the system continuously. The problem is solved by reducing the constrained continuous problem to an unconstrained discrete one. It is shown that the separation principle for estimation and control still holds for this problem when the plant disturbance and measurement noise are Gaussian.

Experimental Study of Dispersion and Deposition of Expiratory Aerosols in Aircraft Cabins and Impact on Infectious Disease Transmission

DEFF Research Database (Denmark)

To, G.N.S.; Wan, M.P.; Chao, C.Y.H.

2009-01-01

The dispersion and deposition characteristics of polydispersed expiratory aerosols were investigated in an aircraft cabin mockup to study the transmission of infectious diseases. The airflow was characterized by particle image velocimetry (PIV) measurements. Aerosol dispersionwas measured...

Sound Control in the Physic Lab in the Polyacryl Company and Studying the Noise Reduction by Means of Different Absorbents

Directory of Open Access Journals (Sweden)

Harandi

1999-03-01

Full Text Available Studying noise effect at the workplace has more various aspects than other factors. So it is not surprising that its adverse impact on the physical and mental state of the society has been detected to some extent. There is a significant correlation between the hearing loss and the noise pollution of the workplaces. The most important ways to lessen and control the impact of noise are: substituting the noisy equipments with ones that produce less noise, correcting noise sources and isolating the sound source. In the current study we tried to control the noise level by using various sound absorbents and measured sound level by using these different substances. The results of these measurements have reported in the current article in details.

Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

Science.gov (United States)

Revell, J. D.; Balena, F. J.; Koval, L. R.

1980-01-01

The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

High efficiency cabin air filter in vehicles reduces drivers' roadway particulate matter exposures and associated lipid peroxidation.

Science.gov (United States)

Yu, Nu; Shu, Shi; Lin, Yan; She, Jianwen; Ip, Ho Sai Simon; Qiu, Xinghua; Zhu, Yifang

2017-01-01

Commuters who spend long hours on roads are exposed to high levels of traffic related air pollutants (TRAPs). Despite some well-known multiple adverse effects of TRAPs on human health, limited studies have focused on mitigation strategies to reduce these effects. In this study, we measured fine particulate matter (PM2.5) and ultrafine particle (UFP) concentrations inside and outside 17 taxis simultaneously while they were driven on roadways. The drivers' urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and malondialdehyde (MDA) concentrations just before and right after the driving tests were also determined. Data were collected under three driving conditions (i.e. no mitigation (NM), window closed (WC), and window closed plus using high efficiency cabin air filters (WC+HECA)) for each taxi and driver. The results show that, compared to NM, the WC+HECA reduced in-cabin PM2.5 and UFP concentrations, by 37% and 47% respectively (p health.

Comparison of Auditory Brainstem Response in Noise Induced Tinnitus and Non-Tinnitus Control Subjects

Directory of Open Access Journals (Sweden)

Ghassem Mohammadkhani

2009-12-01

Full Text Available Background and Aim: Tinnitus is an unpleasant sound which can cause some behavioral disorders. According to evidence the origin of tinnitus is not only in peripheral but also in central auditory system. So evaluation of central auditory system function is necessary. In this study Auditory brainstem responses (ABR were compared in noise induced tinnitus and non-tinnitus control subjects.Materials and Methods: This cross-sectional, descriptive and analytic study is conducted in 60 cases in two groups including of 30 noise induced tinnitus and 30 non-tinnitus control subjects. ABRs were recorded ipsilateraly and contralateraly and their latencies and amplitudes were analyzed.Results: Mean interpeak latencies of III-V (p= 0.022, I-V (p=0.033 in ipsilatral electrode array and mean absolute latencies of IV (p=0.015 and V (p=0.048 in contralatral electrode array were significantly increased in noise induced tinnitus group relative to control group. Conclusion: It can be concluded from that there are some decrease in neural transmission time in brainstem and there are some sign of involvement of medial nuclei in olivery complex in addition to lateral lemniscus.

Designing and Manufacturing a Noise Controlling Silencer for the Cooling Tower Pump of Sarcheshmeh Copper Power Station

Directory of Open Access Journals (Sweden)

Sajad Zare

2017-08-01

Full Text Available Background One of the most common harmful factors in the workplace is noise. Noise control is a factor beneficial for health and safety in the workplace. Objectives The current study aimed to design and manufacture a silencer for the cooling tower pump of Sarcheshmeh Copper power station in order to control noise. Methods In this study, sound pressure level was measured by the use of a sound level meter (B & K 2260. Measurement was carried out in the light of ISO 1996 standard. After studying technical and acoustic features of the noise source, a dispersive-absorptive silencer was designed to control noise pollution generated by the cooling tower pump of the thermal station. After analyzing the frequencies of sound pressure level and using available data, a cylindrical silencer (with a diameter of 1.5 m and height of 3 m was designed and manufactured. The internal part of the silencer was filled with different columns of absorbent material covered with punched metal. Therefore, the silencer consisted of (1 acoustic diffuser, (2 acoustic chamber, and (3 acoustic channels. Results Measurements showed that, at a distance of 1 m from the source, sound pressure level reduced from 127 dBA before installing the silencer to 79 dBA after the installation, resulting in a reduction of 48 dBA. Conclusions Using a silencer with absorbent material (glass wool is very effective in reducing the noise generated by the pump.

Investigation of in-cabin volatile organic compounds (VOCs) in taxis; influence of vehicle's age, model, fuel, and refueling.

Science.gov (United States)

Bakhtiari, Reza; Hadei, Mostafa; Hopke, Philip K; Shahsavani, Abbas; Rastkari, Noushin; Kermani, Majid; Yarahmadi, Maryam; Ghaderpoori, Afshin

2018-06-01

The air pollutant species and concentrations in taxis' cabins can present significant health impacts on health. This study measured the concentrations of benzene, toluene, ethylbenzene, xylene (BTEX), formaldehyde, and acetaldehyde in the cabins of four different taxi models. The effects of taxi's age, fuel type, and refueling were investigated. Four taxi models in 3 age groups were fueled with 3 different fuels (gas, compressed natural gas (CNG), and liquefied petroleum gas (LPG)), and the concentrations of 6 air pollutants were measured in the taxi cabins before and after refueling. BTEX, formaldehyde, and acetaldehyde sampling were actively sampled using NIOSH methods 1501, 2541, and 2538, respectively. The average BTEX concentrations for all taxi models were below guideline values. The average concentrations (±SD) of formaldehyde in Model 1 to Model 4 taxis were 889 (±356), 806 (±323), 1144 (±240), and 934 (±167) ppbv, respectively. Acetaldehyde average concentrations (±SD) in Model 1 to Model 4 taxis were 410 (±223), 441 (±241), 443 (±210), and 482 (±91) ppbv, respectively. Refueling increased the in-vehicle concentrations of pollutants primarily the CNG and LPG fuels. BTEX concentrations in all taxi models were significantly higher for gasoline. Taxi age inversely affected formaldehyde and acetaldehyde. In conclusion, it seems that refueling process and substitution of gasoline with CNG and LPG can be considered as solutions to improve in-vehicle air concentrations for taxis. Copyright © 2018. Published by Elsevier Ltd.

Stabilization of Barkhausen noise readings by controlling a surface field waveform

Czech Academy of Sciences Publication Activity Database

Stupakov, Oleksandr

2014-01-01

Roč. 25, č. 1 (2014), s. 1-8 ISSN 0957-0233 R&D Projects: GA ČR GA13-18993S Institutional support: RVO:68378271 Keywords : magnetic Barkhausen noise * surface field measurement * digital feedback control * non-destructive testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.433, year: 2014

Digitally controlled active noise reduction with integrated speech communication

NARCIS (Netherlands)

Steeneken, H.J.M.; Verhave, J.A.

2004-01-01

Active noise reduction is a successful addition to passive ear-defenders for improvement of the sound attenuation at low frequencies. Design and assessment methods are discussed, focused on subjective and objective attenuation measurements, stability, and high noise level applications. Active noise

Noise control, sound, and the vehicle design process

Science.gov (United States)

Donavan, Paul

2005-09-01

For many products, noise and sound are viewed as necessary evils that need to be dealt with in order to bring the product successfully to market. They are generally not product ``exciters'' although some vehicle manufacturers do tune and advertise specific sounds to enhance the perception of their products. In this paper, influencing the design process for the ``evils,'' such as wind noise and road noise, are considered in more detail. There are three ingredients to successfully dealing with the evils in the design process. The first of these is knowing how excesses in noise effects the end customer in a tangible manner and how that effects customer satisfaction and ultimately sells. The second is having and delivering the knowledge of what is required of the design to achieve a satisfactory or even better level of noise performance. The third ingredient is having the commitment of the designers to incorporate the knowledge into their part, subsystem or system. In this paper, the elements of each of these ingredients are discussed in some detail and the attributes of a successful design process are enumerated.

ON THE APPLICATION OF PARTIAL BARRIERS FOR SPINNING MACHINE NOISE CONTROL: A THEORETICAL AND EXPERIMENTAL APPROACH

Directory of Open Access Journals (Sweden)

M. R. Monazzam, A. Nezafat

2007-04-01

Full Text Available Noise is one of the most serious challenges in modern community. In some specific industries, according to the nature of process, this challenge is more threatening. This paper describes a means of noise control for spinning machine based on experimental measurements. Also advantages and disadvantages of the control procedure are added. Different factors which may affect the performance of the barrier in this situation are also mentioned. To provide a good estimation of the control measure, a theoretical formula is also described and it is compared with the field data. Good agreement between the results of filed measurements and theoretical presented model was achieved. No obvious noise reduction was seen by partial indoor barriers in low absorbent enclosed spaces, since the reflection from multiple hard surfaces is the main dominated factor in the tested environment. At the end, the situation of the environment and standards, which are necessary in attaining the ideal results, are explained.

Active control of multi-modal propagation of tonal noise in

DEFF Research Database (Denmark)

Laugesen, Søren

1996-01-01

The active control of tonal noise propagating in ducts at frequencies where many modes are able to propagate is considered. The final objective of the work reported is to cancel the prominent 450-500 Hz blade passing frequency of the rotary suction fans found in chimney stacks of power stations...... laboratory. The study of the full control system, which comprises thirty secondary sources and thirty-two error sensors, has revealed a number of new results, in particular with respect to the positioning of the sources and sensors along the length of the duct. Eventually, a reduction of the radiated power...

Odeon, a design tool for auditorium acoustics, noise control and loudspeaker systems

DEFF Research Database (Denmark)

Christensen, Claus Lynge

2001-01-01

The ODEON software was originally developed for prediction of auditorium acoustics. However current editions of the software are not limited to these fields, but also allow prediction in rooms such as churches and mosques, interior noise control, design of room acoustics and sound distribution...

Noise Reduction in Double‿Panel Structures by Cavity and Panel Resonance Control

OpenAIRE

Ho, J.; Berkhoff, Arthur P.

2011-01-01

This paper presents an investigation of the cavity and the panel resonance control in a double‿panel structure. The double‿panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its light weight and effective transmission‿loss at high frequency. However, the resonance of the cavity and the poor transmission‿loss at low frequency limit its noise control performance. Applying active control forces on the panels or utili...

Data-driven adaptive fractional order PI control for PMSM servo system with measurement noise and data dropouts.

Science.gov (United States)

Xie, Yuanlong; Tang, Xiaoqi; Song, Bao; Zhou, Xiangdong; Guo, Yixuan

2018-04-01

In this paper, data-driven adaptive fractional order proportional integral (AFOPI) control is presented for permanent magnet synchronous motor (PMSM) servo system perturbed by measurement noise and data dropouts. The proposed method directly exploits the closed-loop process data for the AFOPI controller design under unknown noise distribution and data missing probability. Firstly, the proposed method constructs the AFOPI controller tuning problem as a parameter identification problem using the modified l p norm virtual reference feedback tuning (VRFT). Then, iteratively reweighted least squares is integrated into the l p norm VRFT to give a consistent compensation solution for the AFOPI controller. The measurement noise and data dropouts are estimated and eliminated by feedback compensation periodically, so that the AFOPI controller is updated online to accommodate the time-varying operating conditions. Moreover, the convergence and stability are guaranteed by mathematical analysis. Finally, the effectiveness of the proposed method is demonstrated both on simulations and experiments implemented on a practical PMSM servo system. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

Science.gov (United States)

Bagha, Ashok K; Modak, S V

2015-07-01

This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy.

Advanced Noise Control Fan: A 20-Year Retrospective

Science.gov (United States)

Sutliff, Dan

2016-01-01

The ANCF test bed is used for evaluating fan noise reduction concepts, developing noise measurement technologies, and providing a database for Aero-acoustic code development. Rig Capabilities: 4 foot 16 bladed rotor @ 2500 rpm, Auxiliary air delivery system (3 lbm/sec @ 6/12 psi), Variable configuration (rotor pitch angle, stator count/position, duct length), synthetic acoustic noise generation (tone/broadband). Measurement Capabilities: 112 channels dynamic data system, Unique rotating rake mode measuremen, Farfield (variable radius), Duct wall microphones, Stator vane microphones, Two component CTA w/ traversing, ESP for static pressures.

Noise promotes independent control of gamma oscillations and grid firing within recurrent attractor networks

Science.gov (United States)

Solanka, Lukas; van Rossum, Mark CW; Nolan, Matthew F

2015-01-01

Neural computations underlying cognitive functions require calibration of the strength of excitatory and inhibitory synaptic connections and are associated with modulation of gamma frequency oscillations in network activity. However, principles relating gamma oscillations, synaptic strength and circuit computations are unclear. We address this in attractor network models that account for grid firing and theta-nested gamma oscillations in the medial entorhinal cortex. We show that moderate intrinsic noise massively increases the range of synaptic strengths supporting gamma oscillations and grid computation. With moderate noise, variation in excitatory or inhibitory synaptic strength tunes the amplitude and frequency of gamma activity without disrupting grid firing. This beneficial role for noise results from disruption of epileptic-like network states. Thus, moderate noise promotes independent control of multiplexed firing rate- and gamma-based computational mechanisms. Our results have implications for tuning of normal circuit function and for disorders associated with changes in gamma oscillations and synaptic strength. DOI: http://dx.doi.org/10.7554/eLife.06444.001 PMID:26146940

Exploration Mission Particulate Matter Filtration Technology Performance Testing in a Simulated Spacecraft Cabin Ventilation System

Science.gov (United States)

Agui, Juan H.; Vijayakumar, R.; Perry, Jay L.; Frederick, Kenneth R.; Mccormick, Robert M.

2017-01-01

Human deep space exploration missions will require advances in long-life, low maintenance airborne particulate matter filtration technology. As one of the National Aeronautics and Space Administrations (NASA) developments in this area, a prototype of a new regenerable, multi-stage particulate matter filtration technology was tested in an International Space Station (ISS) module simulation facility. As previously reported, the key features of the filter system include inertial and media filtration with regeneration and in-place media replacement techniques. The testing facility can simulate aspects of the cabin environment aboard the ISS and contains flight-like cabin ventilation system components. The filtration technology test article was installed at the inlet of the central ventilation system duct and instrumented to provide performance data under nominal flow conditions. In-place regeneration operations were also evaluated. The real-time data included pressure drop across the filter stages, process air flow rate, ambient pressure, humidity and temperature. In addition, two video cameras positioned at the filtration technology test articles inlet and outlet were used to capture the mechanical performance of the filter media indexing operation under varying air flow rates. Recent test results are presented and future design recommendations are discussed.

International Space Station USOS Crew Quarters Ventilation and Acoustic Design Implementation

Science.gov (United States)

Broyan, James Lee, Jr.

2009-01-01

The International Space Station (ISS) United States Operational Segment (USOS) has four permanent rack sized ISS Crew Quarters (CQ) providing a private crewmember space. The CQ uses Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air from the ISS Temperature Humidity Control System or the ISS fluid cooling loop connections. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crewmember s head position and reduce acoustic exposure. The CQ interior needs to be below Noise Curve 40 (NC-40). The CQ ventilation ducts are open to the significantly louder Node 2 cabin aisle way which required significantly acoustic mitigation controls. The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

In-Service Performance and Costs of Methods to Control Urban Rail System Noise

Science.gov (United States)

1979-12-01

This study evaluates the acoustic and economic effectiveness of five methods of controlling wheel/rail noise and vibration on urban rail transit systems, namely: rail grinding, wheel truing, resilient wheels, ring-damped wheels, and welded vs. jointe...

Show in the Sky: A Research on Emotional Labor Processes of Cabin Crew

OpenAIRE

İyem, Cemal; Yıldız, Fatma Zehra

2017-01-01

It seems that emotions of the workers gain a commercial quality with internal behaviors as similing entering working life such. The element of emotion requests that the workers must adapt their own feelings to the aim of organization. Competitive politics off service sector have been turning the feelings of workers into pleasure of costumers. In the education of cabin attendants working on the field of aviation sector which emotional labour is very condense, are told to be patient and have ha...

Signal-Noise Ratio Control Subsystem of Digital Equipment for Transmission of "Strela" Relay Protection Commands

Directory of Open Access Journals (Sweden)

I. I. Zabenkov

2012-01-01

Full Text Available Continuous measurement function of relative noise and interference level in the information transmission channel is considered as an important one for controlling parameters of high-frequency signal. The present paper simulates an algorithm for measuring signal-noise ratio in the transmission channel of high-voltage lines which is used in the digital equipment for transmission of relay protection and emergency automation commands of "Strela" complex.

Effect of personal and situational variables on noise annoyance: With special reference to implications for en route noise

Science.gov (United States)

Fields, James M.

1992-08-01

Over 680 publications from 282 social surveys of residents' reactions to environmental noise have been examined to locate 495 published findings on 26 topics concerning non-noise explanations for residents' reactions to environmental noise. This report (1) tabulates the evidence on the 26 response topics, (2) identifies the 495 findings, and (3) discusses the implications for en route noise assessment. After controlling for noise level, over half of the social survey evidence indicates that noise annoyance is not strongly affected by any of the nine demographic variables examined (age, sex, social status, income, education, homeownership, type of dwelling, length of residence, or receipt of benefits from the noise source), but is positively associated with each of the five attitudinal variables examined (a fear of danger from the noise source, a sensitivity towards noise generally, the belief that the authorities can control the noise, the awareness of non-noise impacts of the source, and the belief that the noise source is not important).

Analytical evaluation of the protection offered by sealed tractor cabins during crop pulverization with fenitrothion.

Science.gov (United States)

Barcellos, Michelle; Faletti, Milena Michele; Madureira, Luiz Augusto Dos Santos; Bauer, Fernando Cesar

2016-12-01

The practice of large-scale agriculture requires the use of pesticides in order to maximize production. This activity has gained increasing attention in recent years, especially from rural workers, due to the risks associated with long-term exposure to pesticides. To minimize these risks, personal protection equipment (e.g., covers, gloves, and goggles) and collective protection equipment (e.g., agricultural tractors with sealed cabins) have been developed. In general, these approaches are intended to reduce the contact of farmers and agricultural machinery operators with the more toxic and stable compounds, an example of which is fenitrothion. In this study, fenitrothion was used as a marker to evaluate the protection afforded inside a sealed tractor cabin. To simulate the pesticide exposure, tests were performed using artificial cotton targets as passive adsorptive agents inside the cabin during the pesticide application. Samples were extracted according to the US Environmental Protection Agency (USEPA) procedure using ultrasonic extraction and as proposed by the Brazilian Standard for Solid Waste Classification (NBR 10004). The extracts were analyzed by high-performance liquid chromatography with diode array detection (HPLC-DAD). The chromatographic method was optimized using a factorial design. The combined results indicated that the best conditions were achieved using a mobile phase with a water/acetonitrile ratio of 35:65, a column temperature of 40 °C, and a flow rate of 1.0 mL/min, with a total analysis time of <10 min. The method was evaluated in the linear range of 0.50 to 2.01 mg/kg, with a determination coefficient of 0.9886. The precision was evaluated on different days and the relative standard deviations were between 0.17 and 3.41 %. In relation to the accuracy, recovery values of 95 to 104 % were obtained. The detection and quantification limits were 0.18 and 0.50 mg/kg, respectively. None of the target cottons showed concentrations of

Proceedings of the 2005 spring conference on environmental and occupational noise : for whom the decibel tolls : reducing the impact of noise. CD ed.

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

This conference provided a forum to discuss innovations in noise control and noise management technologies in order to raise awareness about expanding noise issues. Advancements in research, technology and software were presented along with case studies that highlighted current issues associated with noise management, including occupational noise identification, noise measurement, regulations and noise control. The plenary and technical sessions focused on environmental and occupational noise control, industrial noise control and innovative technology. The objective was to promote responsible industrial development and to identify and promote strategies for reducing workplace noise exposure and promote responsible management of human noise exposure. A special session on noise associated with wind turbines was included with particular reference to wind turbine sound and public concerns. Newly developed sound modeling software that can predict sound energy from turbines was also presented. The conference featured 58 presentations, of which 20 have been catalogued separately for inclusion in this database. refs., tabs., figs.

Proceedings of the 2005 spring conference on environmental and occupational noise : for whom the decibel tolls : reducing the impact of noise. CD ed.

International Nuclear Information System (INIS)

2005-01-01

Abstract This conference provided a forum to discuss innovations in noise control and noise management technologies in order to raise awareness about expanding noise issues. Advancements in research, technology and software were presented along with case studies that highlighted current issues associated with noise management, including occupational noise identification, noise measurement, regulations and noise control. The plenary and technical sessions focused on environmental and occupational noise control, industrial noise control and innovative technology. The objective was to promote responsible industrial development and to identify and promote strategies for reducing workplace noise exposure and promote responsible management of human noise exposure. A special session on noise associated with wind turbines was included with particular reference to wind turbine sound and public concerns. Newly developed sound modeling software that can predict sound energy from turbines was also presented. The conference featured 58 presentations, of which 20 have been catalogued separately for inclusion in this database. refs., tabs., figs

Simulation and stability analysis of supersonic impinging jet noise with microjet control

Science.gov (United States)

Hildebrand, Nathaniel; Nichols, Joseph W.

2014-11-01

A model for an ideally expanded 1.5 Mach turbulent jet impinging on a flat plate using unstructured high-fidelity large eddy simulations (LES) and hydrodynamic stability analysis is presented. Note the LES configuration conforms exactly to experiments performed at the STOVL supersonic jet facility of the Florida Center for Advanced Aero-Propulsion allowing validation against experimental measurements. The LES are repeated for different nozzle-wall separation distances as well as with and without the addition of sixteen microjets positioned uniformly around the nozzle lip. For some nozzle-wall distances, but not all, the microjets result in substantial noise reduction. Observations of substantial noise reduction are associated with a relative absence of large-scale coherent vortices in the jet shear layer. To better understand and predict the effectiveness of microjet noise control, the application of global stability analysis about LES mean fields is used to extract axisymmetric and helical instability modes connected to the complex interplay between the coherent vortices, shocks, and acoustic feedback. We gratefully acknowledge computational resources provided by the Argonne Leadership Computing Facility.

The need to revitalize our national noise policy

Science.gov (United States)

Lang, William W.; Beranek, Leo L.

2002-05-01

At the present time, our Nation does not have a national noise policy. The Congress attempted to define one with the passage of the Noise Control Act of 1972 as follows: The Congress declares that it is the policy of the United States to promote an environment for all Americans free from noise that jeopardizes their health and welfare. The Act assigned to the Environmental Protection Agency (EPA) the role of leading Federal agency with the task of coordinating the programs of all Federal agencies relating to noise research and noise control. Ten years later (1982), all funds for noise control were withdrawn from the EPA, and today the Nation is without an effective, overall noise policy. Residual responsibility for the control of environmental and occupational noise currently rests with a dozen agencies of the Federal government, as well as State, municipal, and local authorities. But the activities of these organizations are largely uncoordinated, and the enforcement of existing noise control regulations is at best sporadic, and in some cases nonexistent. To assure our quality of life and to minimize the economic impact of potential trade barriers, a study team is recommending that a national noise policy be developed and then implemented in the immediate future.

Direct oxidation of strong waste waters, simulating combined wastes in extended-mission space cabins

Science.gov (United States)

Ross, L. W.

1973-01-01

The applications of modern technology to the resolution of the problem of solid wastes in space cabin environments was studied with emphasis on the exploration of operating conditions that would permit lowering of process temperatures in wet oxidation of combined human wastes. It was found that the ultimate degree of degradation is not enhanced by use of a catalyst. However, the rate of oxidation is increased, and the temperature of oxidation is reduced to 400 F.

Anticipated Effectiveness of Active Noise Control in Propeller Aircraft Interiors as Determined by Sound Quality Tests

Science.gov (United States)

Powell, Clemans A.; Sullivan, Brenda M.

2004-01-01

Two experiments were conducted, using sound quality engineering practices, to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller aircraft. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Although the results of the two tests were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference.

Validation by numerical simulation of the behaviour of protective structures of machinery cabins subjected to standardized shocks

Science.gov (United States)

Dumitrache, P.; Goanţă, A. M.

2017-08-01

The ability of the cabins to insure the operator protection in the case of the shock loading that appears at the roll-over of the machine or when the cab is struck by the falling objects, it’s one of the most important performance criterions that it must comply by the machines and the mobile equipments. The experimental method provides the most accurate information on the behaviour of protective structures, but generates high costs due to experimental installations and structures which may be compromised during the experiments. In these circumstances, numerical simulation of the actual problem (mechanical shock applied to a strength structure) is a perfectly viable alternative, given that the hardware and software current performances provides the necessary support to obtain results with an acceptable level of accuracy. In this context, the paper proposes using FEA platforms for virtual testing of the actual strength structures of the cabins using their finite element models based on 3D models generated in CAD environments. In addition to the economic advantage above mentioned, although the results obtained by simulation using the finite element method are affected by a number of simplifying assumptions, the adequate modelling of the phenomenon can be a successful support in the design process of structures to meet safety performance criteria imposed by current standards. In the first section of the paper is presented the general context of the security performance requirements imposed by current standards on the cabins strength structures. The following section of the paper is dedicated to the peculiarities of finite element modelling in problems that impose simulation of the behaviour of structures subjected to shock loading. The final section of the paper is dedicated to a case study and to the future objectives.

Modeling of Broadband Liners Applied to the Advanced Noise Control Fan

Science.gov (United States)

Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.

2015-01-01

The broadband component of fan noise has grown in relevance with an increase in bypass ratio and incorporation of advanced fan designs. Therefore, while the attenuation of fan tones remains a major factor in engine nacelle acoustic liner design, the simultaneous reduction of broadband fan noise levels has received increased interest. As such, a previous investigation focused on improvements to an established broadband acoustic liner optimization process using the Advanced Noise Control Fan (ANCF) rig as a demonstrator. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom liner designs were carried through design, fabrication, and testing. This paper addresses a number of areas for further research identified in the initial assessment of the ANCF study. Specifically, incident source specification and uncertainty in some aspects of the predicted liner impedances are addressed. This information is incorporated in updated predictions of the liner performance and comparisons with measurement are greatly improved. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of various liner designs. This study also provides further confidence in the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

Self-organized critical noise amplification in human closed loop control

Directory of Open Access Journals (Sweden)

Felix Patzelt

2007-11-01

Full Text Available When humans perform closed loop control tasks like in upright standing or while balancing a stick, their behavior exhibits non-Gaussian fluctuations with long-tailed distributions. The origin of these fluctuations is not known. Here, we investigate if they are caused by selforganized critical noise amplification which emerges in control systems when an unstable dynamics becomes stabilized by an adaptive controller that has finite memory. Starting from this theory, we formulate a realistic model of adaptive closed loop control by including constraints on memory and delays. To test this model, we performed psychophysical experiments where humans balanced an unstable target on a screen. It turned out that the model reproduces the long tails of the distributions together with other characteristic features of the human control dynamics. Fine-tuning the model to match the experimental dynamics identifies parameters characterizing a subject’s control system which can be independently tested. Our results suggest that the nervous system involved in closed loop motor control nearly optimally estimates system parameters on-line from very short epochs of past observations.

Filtered-X Affine Projection Algorithms for Active Noise Control Using Volterra Filters

Directory of Open Access Journals (Sweden)

Sicuranza Giovanni L

2004-01-01

Full Text Available We consider the use of adaptive Volterra filters, implemented in the form of multichannel filter banks, as nonlinear active noise controllers. In particular, we discuss the derivation of filtered-X affine projection algorithms for homogeneous quadratic filters. According to the multichannel approach, it is then easy to pass from these algorithms to those of a generic Volterra filter. It is shown in the paper that the AP technique offers better convergence and tracking capabilities than the classical LMS and NLMS algorithms usually applied in nonlinear active noise controllers, with a limited complexity increase. This paper extends in two ways the content of a previous contribution published in Proc. IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03, Grado, Italy, June 2003. First of all, a general adaptation algorithm valid for any order of affine projections is presented. Secondly, a more complete set of experiments is reported. In particular, the effects of using multichannel filter banks with a reduced number of channels are investigated and relevant results are shown.

Kalman filter based fault diagnosis of networked control system with white noise

Institute of Scientific and Technical Information of China (English)

Yanwei WANG; Ying ZHENG

2005-01-01

The networked control system NCS is regarded as a sampled control system with output time-variant delay.White noise is considered in the model construction of NCS.By using the Kalman filter theory to compute the filter parameters,a Kalman filter is constructed for this NCS.By comparing the output of the filter and the practical system,a residual is generated to diagnose the sensor faults and the actuator faults.Finally,an example is given to show the feasibility of the approach.

An alternative method for noise analysis using pixel variance as part of quality control procedures on digital mammography systems

International Nuclear Information System (INIS)

Bouwman, R; Broeders, M; Van Engen, R; Young, K; Lazzari, B; Ravaglia, V

2009-01-01

According to the European Guidelines for quality assured breast cancer screening and diagnosis, noise analysis is one of the measurements that needs to be performed as part of quality control procedures on digital mammography systems. However, the method recommended in the European Guidelines does not discriminate sufficiently between systems with and without additional noise besides quantum noise. This paper attempts to give an alternative and relatively simple method for noise analysis which can divide noise into electronic noise, structured noise and quantum noise. Quantum noise needs to be the dominant noise source in clinical images for optimal performance of a digital mammography system, and therefore the amount of electronic and structured noise should be minimal. For several digital mammography systems, the noise was separated into components based on the measured pixel value, standard deviation (SD) of the image and the detector entrance dose. The results showed that differences between systems exist. Our findings confirm that the proposed method is able to discriminate systems based on their noise performance and is able to detect possible quality problems. Therefore, we suggest to replace the current method for noise analysis as described in the European Guidelines by the alternative method described in this paper.

Current reversal in a continuously periodic system driven by an additive noise and a multiplicative noise

International Nuclear Information System (INIS)

Wang Canjun; Chen Shibo; Mei Dongcheng

2006-01-01

We study the noise-induce transport and current reversal of Brownian particles in a continuously periodic potential driven by cross correlation between a multiplicative white noise and an additive white noise. We find that directed motion of the Brownian particles can be induced by the correlation between the additive noise and the multiplicative noise. The current reversal and the direction of the current is controlled by the values of the intensity (λ) of the correlated noises and a dimensionless parameter R (R=α/D, D is the intensity of multiplicative noise and α is the intensity of additive noise)

Controlling noise-induced behavior of excitable networks

International Nuclear Information System (INIS)

Patidar, S; Pototsky, A; Janson, N B

2009-01-01

The paper demonstrates the possibility to control the collective behavior of a large network of excitable stochastic units, in which oscillations are induced merely by external random input. Each network element is represented by the FitzHugh-Nagumo system under the influence of noise, and the elements are coupled through the mean field. As known previously, the collective behavior of units in such a network can range from synchronous to non-synchronous spiking with a variety of states in between. We apply the Pyragas delayed feedback to the mean field of the network and demonstrate that this technique is capable of suppressing or weakening the collective synchrony, or of inducing the synchrony where it was absent. On the plane of control parameters we indicate the areas where suppression of synchrony is achieved. To explain the numerical observations on a qualitative level, we use the semi-analytic approach based on the cumulant expansion of the distribution density within Gaussian approximation. We perform bifurcation analysis of the obtained cumulant equations with delay and demonstrate that the regions of stability of its steady state have qualitatively the same structure as the regions of synchrony suppression of the original stochastic equations. We also demonstrate the delay-induced multistability in the stochastic network. These results are relevant to the control of unwanted behavior in neural networks.

Modal Parameters Evaluation in a Full-Scale Aircraft Demonstrator under Different Environmental Conditions Using HS 3D-DIC

Directory of Open Access Journals (Sweden)

Ángel Jesús Molina-Viedma

2018-02-01

Full Text Available In real aircraft structures the comfort and the occupational performance of crewmembers and passengers are affected by the presence of noise. In this sense, special attention is focused on mechanical and material design for isolation and vibration control. Experimental characterization and, in particular, experimental modal analysis, provides information for adequate cabin noise control. Traditional sensors employed in the aircraft industry for this purpose are invasive and provide a low spatial resolution. This paper presents a methodology for experimental modal characterization of a front fuselage full-scale demonstrator using high-speed 3D digital image correlation, which is non-invasive, ensuring that the structural response is unperturbed by the instrumentation mass. Specifically, full-field measurements on the passenger window area were conducted when the structure was excited using an electrodynamic shaker. The spectral analysis of the measured time-domain displacements made it possible to identify natural frequencies and full-field operational deflection shapes. Changes in the modal parameters due to cabin pressurization and the behavior of different local structural modifications were assessed using this methodology. The proposed full-field methodology allowed the characterization of relevant dynamic response patterns, complementing the capabilities provided by accelerometers.

Active control of noise amplification in the flow over a square leading-edge flat plate utilizing DBD plasma actuator

Science.gov (United States)

Yadong, HUANG; Benmou, ZHOU

2018-05-01

Perturbation is generally considered as the flow noise, and its energy can gain transient growth in the separation bubble. The amplified perturbations may cause unstable Kelvin–Helmohltz vortices which induce the three-dimensional transition. Active control of noise amplification via dielectric barrier discharge plasma actuator in the flow over a square leading-edge flat plate is numerically studied. The actuator is installed near the plate leading-edge where the separation bubble is formed. The maximum energy amplification of perturbations is positively correlated with the separation bubble scale which decreases with the increasing control parameters. As the magnitude of noise amplification is reduced, the laminar-turbulent transition is successfully suppressed.

Visuo-manual tracking: does intermittent control with aperiodic sampling explain linear power and non-linear remnant without sensorimotor noise?

Science.gov (United States)

Gollee, Henrik; Gawthrop, Peter J; Lakie, Martin; Loram, Ian D

2017-11-01

A human controlling an external system is described most easily and conventionally as linearly and continuously translating sensory input to motor output, with the inevitable output remnant, non-linearly related to the input, attributed to sensorimotor noise. Recent experiments show sustained manual tracking involves repeated refractoriness (insensitivity to sensory information for a certain duration), with the temporary 200-500 ms periods of irresponsiveness to sensory input making the control process intrinsically non-linear. This evidence calls for re-examination of the extent to which random sensorimotor noise is required to explain the non-linear remnant. This investigation of manual tracking shows how the full motor output (linear component and remnant) can be explained mechanistically by aperiodic sampling triggered by prediction error thresholds. Whereas broadband physiological noise is general to all processes, aperiodic sampling is associated with sensorimotor decision making within specific frontal, striatal and parietal networks; we conclude that manual tracking utilises such slow serial decision making pathways up to several times per second. The human operator is described adequately by linear translation of sensory input to motor output. Motor output also always includes a non-linear remnant resulting from random sensorimotor noise from multiple sources, and non-linear input transformations, for example thresholds or refractory periods. Recent evidence showed that manual tracking incurs substantial, serial, refractoriness (insensitivity to sensory information of 350 and 550 ms for 1st and 2nd order systems respectively). Our two questions are: (i) What are the comparative merits of explaining the non-linear remnant using noise or non-linear transformations? (ii) Can non-linear transformations represent serial motor decision making within the sensorimotor feedback loop intrinsic to tracking? Twelve participants (instructed to act in three prescribed

Expansion connection of socket in flow distributed cabin of heavy water research reactor inner shell

International Nuclear Information System (INIS)

Jiang Zhiliang; Li Yanshui

1995-01-01

Expansion connection of aluminium alloy LT21 socket in flow distributed cabin of Heavy Water Research Reactor (HWRR) inner shell is described systematically. The expansion connection technology parameters of products are determined through tests. They are as following: bounce value of inner diameter after expansion, expansion degree, space between socket and plate hole, device for expanding pipes, selection of tools for enlarging or reaming holes, manufacture for socket inner hole and cleaning after expansion

Noise Pollution--What can be Done?

Science.gov (United States)

Shaw, Edgar A. G.

1975-01-01

Discusses the ratio of energy dissipated as sound to the mechanical output of devices. Considers noise levels, ranges vs. peaks, noise indexes, and health hazards. Indicates some problems vs. solutions in the technology of noise control. (GH)

49 CFR 39.39 - How do PVOs ensure that passengers with disabilities are able to use accessible cabins?

Science.gov (United States)

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false How do PVOs ensure that passengers with disabilities are able to use accessible cabins? 39.39 Section 39.39 Transportation Office of the Secretary of... to Services § 39.39 How do PVOs ensure that passengers with disabilities are able to use accessible...

Thru-life impacts of driver aggression, climate, cabin thermal management, and battery thermal management on battery electric vehicle utility

Science.gov (United States)

Neubauer, Jeremy; Wood, Eric

2014-08-01

Battery electric vehicles (BEVs) offer the potential to reduce both oil imports and greenhouse gas emissions, but have a limited utility that is affected by driver aggression and effects of climate-both directly on battery temperature and indirectly through the loads of cabin and battery thermal management systems. Utility is further affected as the battery wears through life in response to travel patterns, climate, and other factors. In this paper we apply the National Renewable Energy Laboratory's Battery Lifetime Analysis and Simulation Tool for Vehicles (BLAST-V) to examine the sensitivity of BEV utility to driver aggression and climate effects over the life of the vehicle. We find the primary challenge to cold-climate BEV operation to be inefficient cabin heating systems, and to hot-climate BEV operation to be high peak on-road battery temperatures and excessive battery degradation. Active cooling systems appear necessary to manage peak battery temperatures of aggressive, hot-climate drivers, which can then be employed to maximize thru-life vehicle utility.

Annoyance rating of wind turbine noise

International Nuclear Information System (INIS)

Iredale, R.

1993-01-01

Annoyance rating is important, but more important still is agreement on techniques for formulating minimal complaint criteria for design and specification purposes thus integrating noise control into the plant at the outset. A minimal complaint design criteria is suggested that finds its origin in the logic and techniques used successfully over many years for a wide range of power plant and other installations. The criterion is based on the masking of the wind turbine noise by the wind generated background noise. Satisfactory use of the criterion depends on the specification of inaudibility for the tones generated by the mechanical plant. Wind turbines generate more drive train noise than is realized and this contains many tones which tend to characterize the noise. Reduction of drive train noise would not only reduce the overall noise level but also give it a more acceptable character providing a margin against complaint in unusual circumstances of propagation. This requires very careful design of noise and vibration control in individual components. Vibration isolation between the support structures and the nacelle also requires careful attention. (UK)

Improved Broadband Liner Optimization Applied to the Advanced Noise Control Fan

Science.gov (United States)

Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.; Ayle, Earl; Ichihashi, Fumitaka

2014-01-01

The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more desirable. This paper describes improvements to a previously established broadband acoustic liner optimization process using the Advanced Noise Control Fan rig as a demonstrator. Specifically, in-duct attenuation predictions with a statistical source model are used to obtain optimum impedance spectra over the conditions of interest. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom designs are carried through design, fabrication, and testing to validate the efficacy of the design process. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of these liner designs. This study also provides an application for demonstrating the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

Standard Test Method to Determine Color Change and Staining Caused by Aircraft Maintenance Chemicals upon Aircraft Cabin Interior Hard Surfaces

CERN Document Server

American Society for Testing and Materials. Philadelphia

2001-01-01

1.1 This test method covers the determination of color change and staining from liquid solutions, such as cleaning or disinfecting chemicals or both, on painted metallic surfaces and nonmetallic surfaces of materials being used inside the aircraft cabin. The effects upon the exposed specimens are measured with the AATCC Gray Scale for Color Change and AATCC Gray Color Scale for Staining. Note 1—This test method is applicable to any colored nonmetallic hard surface in contact with liquids. The selected test specimens are chosen because these materials are present in the majority of aircraft cabin interiors. 1.2This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Layout Design of Human-Machine Interaction Interface of Cabin Based on Cognitive Ergonomics and GA-ACA

Directory of Open Access Journals (Sweden)

Li Deng

2016-01-01

Full Text Available In order to consider the psychological cognitive characteristics affecting operating comfort and realize the automatic layout design, cognitive ergonomics and GA-ACA (genetic algorithm and ant colony algorithm were introduced into the layout design of human-machine interaction interface. First, from the perspective of cognitive psychology, according to the information processing process, the cognitive model of human-machine interaction interface was established. Then, the human cognitive characteristics were analyzed, and the layout principles of human-machine interaction interface were summarized as the constraints in layout design. Again, the expression form of fitness function, pheromone, and heuristic information for the layout optimization of cabin was studied. The layout design model of human-machine interaction interface was established based on GA-ACA. At last, a layout design system was developed based on this model. For validation, the human-machine interaction interface layout design of drilling rig control room was taken as an example, and the optimization result showed the feasibility and effectiveness of the proposed method.

Layout Design of Human-Machine Interaction Interface of Cabin Based on Cognitive Ergonomics and GA-ACA.

Science.gov (United States)

Deng, Li; Wang, Guohua; Yu, Suihuai

2016-01-01

In order to consider the psychological cognitive characteristics affecting operating comfort and realize the automatic layout design, cognitive ergonomics and GA-ACA (genetic algorithm and ant colony algorithm) were introduced into the layout design of human-machine interaction interface. First, from the perspective of cognitive psychology, according to the information processing process, the cognitive model of human-machine interaction interface was established. Then, the human cognitive characteristics were analyzed, and the layout principles of human-machine interaction interface were summarized as the constraints in layout design. Again, the expression form of fitness function, pheromone, and heuristic information for the layout optimization of cabin was studied. The layout design model of human-machine interaction interface was established based on GA-ACA. At last, a layout design system was developed based on this model. For validation, the human-machine interaction interface layout design of drilling rig control room was taken as an example, and the optimization result showed the feasibility and effectiveness of the proposed method.

Development of a Prototype Algal Reactor for Removing CO2 from Cabin Air

Science.gov (United States)

Patel, Vrajen; Monje, Oscar

2013-01-01

Controlling carbon dioxide in spacecraft cabin air may be accomplished using algal photobioreactors (PBRs). The purpose of this project was to evaluate the use of a commercial microcontroller, the Arduino Mega 2560, for measuring key photioreactor variables: dissolved oxygen, pH, temperature, light, and carbon dioxide. The Arduino platform is an opensource physical computing platform composed of a compact microcontroller board and a C++/C computer language (Arduino 1.0.5). The functionality of the Arduino platform can be expanded by the use of numerous add-ons or 'shields'. The Arduino Mega 2560 was equipped with the following shields: datalogger, BNC shield for reading pH sensor, a Mega Moto shield for controlling CO2 addition, as well as multiple sensors. The dissolved oxygen (DO) probe was calibrated using a nitrogen bubbling technique and the pH probe was calibrated via an Omega pH simulator. The PBR was constructed using a 2 L beaker, a 66 L box for addition of CO2, a micro porous membrane, a diaphragm pump, four 25 watt light bulbs, a MasterFiex speed controller, and a fan. The algae (wild type Synechocystis PCC6803) was grown in an aerated flask until the algae was dense enough to used in the main reactor. After the algae was grown, it was transferred to the 2 L beaker where CO2 consumption and O2 production was measured using the microcontroller sensor suite. The data was recorded via the datalogger and transferred to a computer for analysis.

Noise Response Data Reveal Novel Controllability Gramian for Nonlinear Network Dynamics

Science.gov (United States)

Kashima, Kenji

2016-01-01

Control of nonlinear large-scale dynamical networks, e.g., collective behavior of agents interacting via a scale-free connection topology, is a central problem in many scientific and engineering fields. For the linear version of this problem, the so-called controllability Gramian has played an important role to quantify how effectively the dynamical states are reachable by a suitable driving input. In this paper, we first extend the notion of the controllability Gramian to nonlinear dynamics in terms of the Gibbs distribution. Next, we show that, when the networks are open to environmental noise, the newly defined Gramian is equal to the covariance matrix associated with randomly excited, but uncontrolled, dynamical state trajectories. This fact theoretically justifies a simple Monte Carlo simulation that can extract effectively controllable subdynamics in nonlinear complex networks. In addition, the result provides a novel insight into the relationship between controllability and statistical mechanics. PMID:27264780

Noise upon the Sinusoids

DEFF Research Database (Denmark)

Jensen, Karl Kristoffer

2005-01-01

Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity’s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...

Simulator with integrated HW and SW for prediction of thermal comfort to provide feedback to the climate control system

Science.gov (United States)

Pokorný, Jan; Kopečková, Barbora; Fišer, Jan; JÍcha, Miroslav

2018-06-01

The aim of the paper is to assemble a simulator for evaluation of thermal comfort in car cabins in order to give a feedback to the HVAC (heating, ventilation and air conditioning) system. The HW (hardware) part of simulator is formed by thermal manikin Newton and RH (relative humidity), velocity and temperature probes. The SW (software) part consists of the Thermal Comfort Analyser (using ISO 14505-2) and Virtual Testing Stand of Car Cabin defining the heat loads of car cabin. Simulator can provide recommendation for the climate control how to improve thermal comfort in cabin by distribution and directing of air flow, and also by amount of ventilation power to keep optimal temperature inside a cabin. The methods of evaluation of thermal comfort were verified by tests with 10 test subjects for summer (summer clothing, ambient air temperature 30 °C, HVAC setup: +24 °C auto) and winter conditions (winter clothing, ambient air temperature -5 °C, HVAC setup: +18 °C auto). The tests confirmed the validity of the thermal comfort evaluation using the thermal manikin and ISO 14505-2.

AN ADAPTIVE OPTIMAL KALMAN FILTER FOR STOCHASTIC VIBRATION CONTROL SYSTEM WITH UNKNOWN NOISE VARIANCES

Institute of Scientific and Technical Information of China (English)

Li Shu; Zhuo Jiashou; Ren Qingwen

2000-01-01

In this paper, an optimal criterion is presented for adaptive Kalman filter in a control sys tem with unknown variances of stochastic vibration by constructing a function of noise variances and minimizing the function. We solve the model and measure variances by using DFP optimal method to guarantee the results of Kalman filter to be optimized. Finally, the control of vibration can be implemented by LQG method.

Noise and noise disturbances from wind power plants - Tests with interactive control of sound parameters for more comfortable and less perceptible sounds

International Nuclear Information System (INIS)

Persson-Waye, K.; Oehrstroem, E.; Bjoerkman, M.; Agge, A.

2001-12-01

In experimental pilot studies, a methodology has been worked out for interactively varying sound parameters in wind power plants. In the tests, 24 persons varied the center frequency of different band-widths, the frequency of a sinus-tone and the amplitude-modulation of a sinus-tone in order to create as comfortable a sound as possible. The variations build on the noise from the two wind turbines Bonus and Wind World. The variations were performed with a constant dba level. The results showed that the majority preferred a low-frequency tone (94 Hz and 115 Hz for Wind World and Bonus, respectively). The mean of the most comfortable amplitude-modulation varied between 18 and 22 Hz, depending on the ground frequency. The mean of the center-frequency for the different band-widths varied from 785 to 1104 Hz. In order to study the influence of the wind velocity on the acoustic character of the noise, a long-time measurement program has been performed. A remotely controlled system has been developed, where wind velocity, wind direction, temperature and humidity are registered simultaneously with the noise. Long-time registrations have been performed for four different wing turbines