Search results

This study aims to learn the dynamic radar cross-section (RCS) of a deflection air brake.

The aircraft model with delta wing, V-shaped tail and blended wing body is designed, and high-precision unstructured grid technology is used to deal with the surface of air brake and fuselage. The calculation method based on multiple tracking and dynamic scattering is presented to calculate RCS.

The fuselage has a low scattering level, and the opening air brake will bring obvious dynamic RCS effects to itself and the whole machine. The average indicator of air brake RCS can be lower than –0.6 dBm² under the tail azimuth, while that of forward and lateral direction is lower. The mean RCS of fuselage is obviously higher than that of air brake, while the deflected air brake and its cabin can still provide strong scattering sources at some azimuths. When the air brake is opening, the change amplitude of the aircraft forward RCS can exceed 19.81 dBm².

This research has practical significance for the dynamic electromagnetic scattering analysis and stealth design of the air brake.

The calculation method for aircraft RCS considering air brake dynamic deflection has been established.

CONVENTIONAL aircraft thermometers are of the platinum‐resistance type, comprising one arm of a Wheatstone bridge network. The meter connected to the network is graduated on a temperature scale and different values are due to changes in the resistance of the platinum element. These arise from variations in the temperature of the air immediately in contact with the element or its protective casing. Any indicated temperature is a measure of the temperature of the air in contact with the thermometer. It is also the temperature of those parts of the aircraft over which the air is moving at the same speed as it is flowing past the thermometer. Since the air does not flow at the same speed over all parts of the aircraft it is clear that by mounting thermometers in different positions on an aircraft, different temperatures will be obtained. Due mainly to kinetic heating none of these will be the true temperature of the air in the free stream—i.e. away from the influence of the aircraft—and to obtain the free stream air temperature it is necessary to apply corrections. For many purposes, particularly meteorological research, it is important to be able to obtain true air temperatures from indicated air temperatures quickly and accurately and it is with this purpose in mind that the diagram to be described was devised and constructed.

The polymer air-drawing model of spunbonding nonwovens has been established. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have also been studied. The paper aims to discuss these issues.

TDMA method is used to solve the difference equations.

It can be concluded that a lower polymer throughput rate, a higher polymer melt initial temperature, a higher air initial temperature, and a higher air initial velocity can all produce finer fibers.

The results also reveal the great potential for this research in the computer-assisted design of spunbonding technology.

The purpose of this paper is to present the results of the preliminary design and optimization of the air-intake system and the engine nacelle. The work was conducted as part of an integration process of a turboprop engine in a small aircraft in a tractor configuration.

The preliminary design process was performed using a parametric, interactive design approach. The parametric model of the aircraft was developed using the PARADES™ in-house software. The model assumed a high level of freedom concerning shaping all the components of aircraft important from the point of view of the engine integration. Additionally, the software was used to control the fulfillment of design constraints and to analyze selected geometrical properties. Based on the developed parametric model, the preliminary design was conducted using the interactive design and optimization methodology. Several concepts of the engine integration were investigated in the process. All components of the aircraft propulsion system were designed simultaneously to ensure their compliance with each other.

The concepts of the engine integration were modified according to changes in the design and technological constraints in the preliminary design process. For the most promising configurations, computational fluid dynamics (CFD) computations were conducted using commercial Reynolds-averaged Navier–Stokes solver FLUENT™ (ANSYS). The simulations tested the flow around the nacelle and inside the air-delivery system which consists of the air-intake duct, the foreign-particles separator and the auxiliary ducts delivering air to the cooling and air-conditioning systems. The effect of the working propeller was modeled using the Virtual Blade Model implemented in the FLUENT code. The flow inside the air-intake system was analyzed from the point of view of minimization of pressure losses in the air-intake duct, the quality of air stream delivered to the engine compressor and the effectiveness of the foreign particles separator.

Based on results of the CFD analyses, the final concept of the turboprop engine integration has been chosen.

The presented results of preliminary design process are valuable to achieve the final goal in the ongoing project.

FEW industries can claim a higher level of technological achievement than aircraft manufacture and it is therefore hardly surprising that this industry should have pioneered and developed many new techniques in the fields of production and testing. Typical of the industry's many contributions to technological advance arc the numerous specialised applications of compressed air which have been introduced by leading airframe, powerplant and aircraft systems manufacturers.

The purpose of this paper is to explore the significance impact of air quality as a contributing factor on residential property rents by applying geo-informatics to economic issues. Since air pollution poses a severe health threat, city residents should have a right to know about the (invisible) hazards they are exposed to.

Within spatial-temporal modeling of air pollutants in Berlin, Germany, three interpolation techniques are tested. The most suitable one is selected to create seasonal maps for 2018 and 2021 with pollution concentrations for particulate matter values and nitrogen dioxide for each 1,000 m² cell within the administrative boundaries. Based on the evaluated pollution particulate matter values, which are used as additional variables for semi-parametric regressions the impact of the air quality on rents is estimated.

The findings reveal a compelling association between air quality and the economic aspect of the residential real estate market, with noteworthy implications for both tenants and property investors. The relationship between air pollution variables and rents is statistically significant. However, there is only a “willingness-to- pay” for low particulate matter values, but not for nitrogen dioxide concentrations. With good air quality, residents in Berlin are willing to pay a higher rent (3%).

These results suggest that a “marginal willingness-to-pay” occurs in a German city. The research underscores the multifaceted impact of air quality on the residential rental market in Berlin. The evidence supports the notion that a cleaner environment not only benefits human health and the planet but also contributes significantly to the economic bottom line of property investors.

The paper has a unique data engineering approach. It collects spatiotemporal data from network of state-certified measuring sites to create an index of air pollution. This spatial information is merged with residential listings. Afterward non-linear regression models are estimated.

The air drawing model plays an important in spunbonding. The purpose of this paper is to study the influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter.

The air drawing model of the polypropylene polymer in a spunbonding process is presented and solved by introducing the numerical computation results of the air flow field of aerodynamic device.

The model prediction of the filament fiber diameter coincides well with the experimental data. The effects of the processing parameters on the filament fiber diameter are discussed. A lower polymer throughput rate, higher polymer melt temperature, higher primary air temperature, higher venturi gap, higher air suction speed, and higher quench pressure can all produce finer filament fiber.

The experimental results show that the agreement between the results and experimental data are very better, which verifies the reliability of these models. The results show great prospects for this research in the field of computer assisted design of spunbonding technology.

The question of the role to be played by air freight in international distribution systems has always been controversial. Airlines have been only too willing to extol what are, by now, the well‐known benefits of air freight: that it can reduce packing, insurance, inventory and warehousing costs, and allow for comparatively risk‐free test marketing. However, within the distribution industry, whilst the usefulness of air freight for emergency and perishable shipments is not in doubt, there is still concern over the high levels of air freight rates compared to those of surface transport, the often poor standards of air freight ground handling, and the limited speed and service advantage which air transport holds over surface operators on short haul routes.

The problem of cyclic variation has been an interesting area of research and has been investigated by many researchers. It is more severe in the case of two‐stroke engines compared with four‐stroke engines. One of the reasons for these cycle‐to‐cycle variations is the variations in the air‐fuel ratios of individual cycles and, if these values of individual cycle air‐fuel ratios are available by some means, they can be used for controlling the cyclic variations. The purpose of this paper is to find a technique to predict the air‐fuel ratio of the individual cycles and use the same for reducing cyclic variations.

In this work, a neuro‐fuzzy model was developed using MATLAB software to compute the air‐fuel ratio of the individual cycles based on the relationship between the air‐fuel ratio and the combustion parameters such as those indicating mean effective pressure (IMEP), crank angle occurrence of peak pressure, and angles of different percentages of heat releases. In‐cylinder pressure traces of 1,000 continuous cycles were measured using a Personal Computer (PC)‐based data acquisition system and an investigation was carried out. The readings were taken for two modes of operations, namely gasoline carburetion and electronic gasoline injection. The engine was loaded by an eddy current dynamometer. The air‐fuel ratio was varied from rich to lean by adjusting the fuel quantity in the carburetion mode and adjusting the pulse width (measure of quantity of fuel to be injected) in the injection mode, at constant throttle. The cyclic variation was identified by the variations in the peak pressures and IMEPs of the individual cycles. The stored data were given as input to the developed neuro‐fuzzy model and, using SIMULINK, the air‐fuel ratios of individual cycles were obtained. These predicted values are fed to the electronic control module (ECM) (meant for injecting the fuel) for refining the pulse width to get cyclic variations reduced.

Results show that cyclic variation increases when the mixture becomes lean. It was also found that cyclic variation in an injected engine was less in comparison with the carbureted engine, as the precise control of air‐fuel mixture was possible in the case of the injected engine.

The technique used in this work may be modified to give more precise pulse width by incorporating various other parameters like exhaust temperature, etc. Future research may be focused to incorporate this system in a moving vehicle to get more fuel efficiency and fewer emissions.

The design of vehicle and engine should be slightly modified to incorporate the ECM and various sensors.

The originality in this paper is that a new technique was developed to find the air‐fuel ratio of individual cycles. This will be useful for the engine manufacturers and for those researchers doing research on the engine side.

The purpose is to present parameters of a new design code, which is intended to control the indoor air environment for sports buildings in China.

Based on requirements of international sports federations the characteristics of indoor airflow of sports buildings in China, include the parameters of indoor air environment of gymnasiums and natatoriums, air velocity, temperature, humidity and fresh air volume. Some illustrations and considerations are shown too.

Compared with the international standards and design guidelines, the Chinese new design code has more detailed parameters for high level sports game.

Not all the indoor air parameters of the code are mentioned in this paper. The designs of sports building are built for high level sports games in recent years of China, the parameters of class A are paid more attention to in the paper.

The contents of paper could be the major designs in heating, ventilation and air conditioning system in sports building.

This paper could be a guide to advice the designing of indoor air environment of sports building, especially for the Beijing Olympic game in 2008, and is useful to help advanced HVAC design and analysis on the similar large space buildings.