Browse Topic: Gravity

Items (939)
The structural stiffness of a manned lunar vehicle is a core indicator ensuring its stable operation in the complex lunar environment. The vehicle’s body structure must meet multiple requirements, including high stiffness, lightweight design, and adaptability to lunar surface conditions. Since lunar gravity is only 1/6 of Earth’s and the terrain is rugged and dusty, the body structure must employ a high-stiffness design to withstand driving impacts and resist deformation, thereby preventing mechanical failures or safety hazards for crew members caused by excessive structural distortion. However, excessive structural stiffness would result in an overweight vehicle body, conflicting with the spacecraft’s lightweight requirements. Thus, the structural stiffness index should be optimized to a lower value while ensuring safe operation during lunar surface driving without compromising performance. This paper calculates and determines the structural bending and torsional stiffness indicators for the manned lunar vehicle’s body through simplified model calculation and the FEA method.
Shen, ZhenghuiWu, YingjiaYang, JianfengWang, WeijunZhang, ChongfengHan, Liangliang
Edge detection is fundamental for intelligent vehicle applications, directly supporting ADAS functions such as lane detection, obstacle recognition, and scene understanding. The conventional Canny edge detection method exhibits notable shortcomings, especially in color-image processing, adaptive threshold selection, and preserving edge integrity under noisy conditions. In this study, we present an enhanced Canny edge detection framework tailored for ADAS-oriented intelligent vehicle systems, incorporating a quaternion-based weighted averaging scheme for color preservation, adaptive thresholds derived from gradient-amplitude histograms, multiscale edge localization via scale multiplication, and a novel gravitational-field-intensity operator for improved gradient robustness. Moreover, we extend the method to vanishing-point estimation an essential ADAS capability by performing precise intersection calculations combined with clustering techniques such as DBSCAN and RANSAC. Experimental evaluations demonstrate that the proposed algorithm markedly outperforms traditional approaches in edge clarity, localization accuracy, and noise resilience, underscoring its promise for strengthening ADAS perception modules in intelligent vehicles.
Uppala, Rohit RajKaye, MuraliZadeh, MehrdadTan, Teik-Khoon
In order to better understand the development level and the degree of development of the transportation network in different areas of the Hexi Corridor, the accessibility of the transportation network in the Hexi Corridor is studied. Firstly, calculate the road density of each county and district in the Hexi Corridor. Then, in view of the topographic characteristics of the Hexi Corridor, introduce the shortest travel time and travel cost into the gravity model, consider the accessibility of both road and railway transportation modes between nodes, construct a comprehensive accessibility model, and analyze the spatial characteristics of the comprehensive accessibility of each county and district in the Hexi Corridor. Secondly, the gravitational model is used to analyze the economic connection intensity among the counties and districts in the Hexi Corridor. Finally, calculate the Gini coefficient, draw the Lorenz curve, and analyze the fairness of the comprehensive accessibility of the Hexi Corridor. Research shows that the comprehensive accessibility and economic connection centrality of each county and district in the Hexi Corridor present a spatial structure of “one belt and one core”, and both the comprehensive accessibility and economic connection centrality show a attenuation from the core area to the strip-shaped area. Liangzhou District of Wuwei City is the main core area of the Hexi Corridor. The Gini coefficient of comprehensive accessibility based on the cumulative proportion of population and GDP is all within the unfair range, and the overall development of the Hexi Corridor and the distribution of the transportation network are unfair. The research results can provide decision support for the optimization of the transportation network, economic development and tourism development in the Hexi Corridor.
Jiang, PingMu, HaiboPeng, Zhiwei
NASA Johnson Space Center has developed the Micro-Organ Device (MOD) platform technology that serves as a drug screening system with human or animal cell micro-organs to supplement and reduce animal studies while potentially increasing the success of clinical trials. The technology was originally developed to evaluate pharmaceuticals in zero gravity to accelerate development and validation of countermeasures for humans in space as well as evaluate space and planetary stressors on a biological level.
Innovators at NASA Johnson Space Center have developed a handheld digital microscope to fill the critical microscopy needs of human space exploration by providing flight crews in situ hematological diagnostic and tracking ability to assess and monitor crew health in the absence of gravity. Although currently in use aboard the International Space Station (ISS) to work in conjunction with NASA’s handheld slide staining system, the microscope may have numerous applications here on Earth.
When Sean Whalen and a couple of friends founded Boost Treadmills LLC in 2017, they’d already helped bring the world its first antigravity treadmill. Now they want the technology to help more people.
The interplay of electrochemistry, two-phase flow, and heat transfer generates complex transport phenomena within the porous materials of fuel cells that are not yet fully understood. This lack of comprehensive understanding complicates the modeling of liquid water transport, which is critical because the hydration of the polymer electrolyte membrane significantly impacts the cell performance. The liquid water transport mechanisms in porous media can be explained by capillary force, hydraulic permeation and gravity effects, as well as water condensation and evaporation. In general, the liquid water transport is mainly driven by the capillary force, while body forces, such as gravity, do not significantly affect its momentum. Due to limited experimental data on capillary pressure and saturation in gas diffusion media, the Leverett approach has been widely used for modeling liquid water transport in PEMFCs. The Leverett approach is a polynomial fitting of capillary pressure data for water imbibition in unconsolidated sand packs. Due to its nature, this approach may not accurately predict capillary pressure in gas diffusion media. Fuel cell GDM materials, naturally hydrophilic, are typically coated with a nonwetting polymer like polytetrafluoroethylene to create hydrophobic surfaces and pores. The resulting nature of GDM materials, with intermediate wettability due to the coexistence of hydrophilic and hydrophobic pore spaces, complicates transport phenomena. Consequently, the applicability of the traditional Leverett approach is questionable. This work focuses on capillary transport within PEMFCs, highlighting key experimental and modeling approaches for predicting the capillary pressure-saturation relationship. Starting from the Leverett function, improved models have been proposed and are here implemented in a 3D-CFD model. This research provides an overview of key experimental and theoretical developments in understanding capillarity in PEMFCs. Furthermore, it implements selected capillary pressure correlations in a 3D-CFD model to evaluate their performance in simulating water transport within the porous media, providing guidelines for their use in large-scale models.
Marra, CarmineCroci, FedericoFontanesi, StefanoBerni, FabioD'Adamo, Alessandro
Automotive seating systems have become increasingly sophisticated, providing consumers with more flexible configurations and comfort functionalities. Traditional power seating, which relied on a few motors to adjust the seat position, has evolved into more technically advanced reconfigurable systems equipped with additional feedback sensors and actuators. These advancements include features such as Easy Entry, Zero Gravity, Stadium Swivel, IP Nesting, Auto Lumbar/Bolster Adjustment and Power Long Rails. All the features indicate that the overall control of seating systems now resembles robotic arm control or multi-body control, involving numerous coordinated movements. In this paper, we propose a novel control strategy for the coordinated speed control of multiple motors. Unlike traditional seating controls, which typically use direct switches or open-loop systems, we introduce a feedback approach that incorporates Kalman-filter-based speed estimation using raw signals directly from Hall Effect sensors. The new proposed method enables the simultaneous coordination and synchronization of multiple motors, ensuring that the seat moves smoothly without colliding with other objects while providing a comfortable experience for the consumer. The design of the control system is discussed in detail, the simulation results and experimental data will be presented and analyzed in relation to the real system.
Yang, HanlongLi, Miranda
SAE TOMORROW TODAY: Launching Human Space Travel with a Luxury Balloon134981/23/2025
Imagine a six-hour journey to outer space that includes a world-class meal, cocktail service, Wi-Fi, and unprecedented views of Earth. This experience could soon become reality. Space Perspective, the world's first carbon-neutral spaceflight experience company, is commercializing space travel with Spaceship Neptune, a pressurized capsule propelled by a giant SpaceBalloon(TM). The experience is designed to be gentle and accessible with no rockets, weightlessness, heavy g-forces, or training required. Alongside world-class meal and cocktail service, space travelers will also enjoy views through the largest windows ever flown to space, Wi-Fi, and a proper restroom. To learn more, we sat down with Taber MacCallum, Founder and Chief Technology Officer, Space Perspective, to discuss the technical development of the SpaceBalloon(TM) and how the company is unlocking the market for space travel in a new and innovative way. We'd love to hear from you. Share your comments, questions and ideas for future topics and guests to podcast@sae.org. Don't forget to take a moment to follow SAE Tomorrow Today--a podcast where we discuss emerging technology and trends in mobility with the leaders, innovators and strategists making it all happen--and give us a review on your preferred podcasting platform. Follow SAE on LinkedIn, Instagram, Facebook, Twitter, and YouTube. Follow host Grayson Brulte on LinkedIn, Twitter, and Instagram.
Hineman, Marcie
Measuring fluid mass in microgravity, where fluid behavior is dominated by fluid properties, is a challenging problem. To address this problem engineers at NASA are developing a capacitance-based, mass-fraction gauge for vessels containing two-phase fluids. The vessel volume is enclosed with an array of electrodes, and a unique set of capacitance measurements of the enclosed volume are made between the electrodes. The capacitance measurements are scaled with appropriate weighting factors derived from Laplace’s Equation to compensate for the highly non-uniform electric fields inside the measurement volume and achieve a greater level of mass fraction accuracy.
The ForgeStar® program, from U.K.-based Space Forge, aims to harness the unique environment of space to create ultra-pure materials that cannot be replicated on Earth. The key opportunities lie in producing high-performance semiconductors and super-alloys with fewer defects and superior properties, thanks to the low-gravity and vacuum conditions of space. Space Forge's ForgeStar satellites will be used to produce advanced materials such as alloys, proteins and semiconductors in the ultra-vacuum and microgravity conditions of space. Manufacturing in low Earth orbit (LEO) has huge potential across sectors from medicine to advanced electronics. Two examples - high frequency amplifiers and super alloys - that Space Forge is focused are described in the next two paragraphs.
We are in the midst of a golden age of space travel with the upcoming launch of multiple reusable heavy lift rockets. These new craft will increase deliverable mass to LEO and decrease delivery costs. These rockets are essential to replacing the ISS with commercial space stations in the coming decade. These new commercial stations will enable the creation of in-space factories that leverage microgravity to improve products for use on Earth. Large-scale 3D bioprinting is one technology that will benefit from microgravity and has the potential to address the organ shortage and overreliance on animal models for drug discovery and testing.
Alongside advancements in automated vehicle technologies, occupants within vehicle compartments are enjoying increased freedom to relax and enjoy their journeys. For instance, reclined seating postures have become more prevalent and comfortable compared to upright seating when Highly Automated Vehicles (HAVs) are introduced. Unfortunately, most Anthropomorphic Testing Devices (ATD) do not support reclined postures. THOR-AV 50M is a specially designed dummy for reclined postures. As a crucial tool for developing safety restraint systems to protect reclined occupants, the first question is how to position it correctly on a reclined seat before impact testing. In this study, classical zero gravity seats were selected. H-point coordinators of selected seat at 25°, 40° and 60° seatback angle were measured and compared by using H-point machine (HPM) even though current HPM was not designed for reclined seat. THOR-AV 50M with loosened joints, served to simulate human relaxation fully when seating on a seat, to explore the most comfortable position, there were two ways of seat adjusting from 25° to 40° and 60°, H-point coordinators of THOR-AV 50M at 40° and 60° were measured, related H-point could be regarded as the most comfortable position. By comparing the measured H-point coordinators of THOR -AV 50M and HPM at 40° and 60°, authors found that deviations were within current regulatory requirement. This finding indicated that the target of H-point of THOR-AV 50M at reclined seating position could be pre-defined by HPM. Therefore, a procedure for positioning the dummy in a reclined seat was developed. This paper provides an explanation of the rationale behind the method by using both physical and virtual dummy finite element models. It serves as a valuable reference for potential updates to related standards and protocols to incorporate reclined seating positions in the future, makes up for blanks in automotive industry.
Liu, ChongqingWang, Zhenwen
Since the atmospheric conditions and gravitational field are different for Mars and Earth, the operating flight environments are different, and necessitate Earth-based appropriate modeling, analysis, and simulation for Mars flight vehicles. This paper compares a hexacopter's flight dynamics in the two environments. The analysis is necessary to determine if a dynamically matched surrogate hexacopter can be designed to conduct reliable testing on Earth, with the goal of successfully operation on Mars. To answer the question, the comprehensive tool FLIGHTLAB® is used to model the hexacopter flight dynamics. Frequency responses in heave, pitch, roll, and yaw rates of the hexacopter in hover are analyzed. The simulation result shows that each attitude response of the designed hexacopter responds very differently in the two environments. The closed-loop response of the hexacopter can be made stable on Earth but not on Mars. Therefore, the proportional feedback technique cannot be utilized to stabilize all four responses altogether. Due to the dynamics of the model being very different in each atmosphere, it is yet not feasible to create a dynamically matched surrogate helicopter that can operate in both environments.
Singh, Raghuvir
The aeroelastic loads, stability and stresses on the Mars Helicopter rotor were predicted with a special-purpose three-dimensional rotor structural dynamic analysis. This paper documents that analysis and the insights gained from it. The thin and cold Martian atmosphere, with density 1% of Earth and speed of sound 30% lower, produced sufficient lift but unusually challenging dynamics even with one third the gravity of Earth. The aeroelastic stability was positive but low-about 10-50 times lower than Earth. The stresses and strains on the 57#x25; thin carbon fiber blades were unsteady, complex, and three-dimensional, but within material limits. The key conclusion was that the Ingenuity rotor was structurally stable and safe for Martian hover and controlled forward flight, even at the lowest Reynolds number and highest Mach number anticipated on Mars. Fundamental gaps remained in basic knowledge and tools which must be addressed for larger more capable rotorcraft of the future.
Datta, AnubhavPatil, MrinalgoudaStaruk, William
Recent experiments by a team from the West Virginia University focused on how a weightless microgravity environment affects 3D printing using titania foam, a material with potential applications ranging from UV blocking to water purification. ACS Applied Materials and Interfaces published their findings.
For both space tourism and space exploration, there is an interest in generating artificial gravity in space for entertainment, recreational, and scientific purposes, as well as to counter the health concerns of extended exposure to a microgravity environment. NASA Ames Research Center has developed a novel technology — a system and approach for creating artificial gravity using a non-rotating spacecraft with connected moving modules, which can be used for habitation and other purposes.
This paper proposes a nonlinear observer for the estimation of gravity vector and angles with respect to velocity vector (flight path angle, bank angle) of a high-performance aircraft. The technique is computationally simpler than the extended Kalman filter (EKF) and hence is suitable for onboard implementations when the digital flight control computer (DFCC) has computational burdens. Flight test data of a highly maneuvering flight such as wind-up turns and full rolls have been used to validate the technique.
Chandrasekaran, KamaliJain, Shikha
Most centrifugal pendulum vibration absorber (CPVA) research focuses on the horizontal or vertical plane, ignoring the influence of gravity. However, with the wide application of CPVAs in the automobile industry, some gravity-related problems have been encountered in practice. In this study, employing the second kind of Lagrange equation, the differential equation of motion of a CPVA is established, and the first-order approximate analytical solution is solved using the method of multiple scales. The mathematical relations among the excitation torque amplitude and phase, gravity influence, absorber trajectory shape, absorber position, viscous damping coefficient, and mistuning level parameters are provided for study. Specifically, the second-order responses of four absorbers and two absorbers in a gravity field are studied, and the influence of the change in the torque excitation phase on the response of the absorber is thoroughly analyzed. The grouping phenomenon in four absorber applications is found during the simulation, and a mathematical explanation is provided. The influence of the absorber viscous damping coefficient on the amplitude and the rotor angular velocity is discussed. To maximize the performance of the CPVA, a damping quality factor Q is defined to compare different end stop positions, and a design principle for the end stop is finally determined. From a mathematical point of view, this explains why a CPVA affects the angular acceleration of the rotor, and the influence of the design parameters on the synchronization and stability of the CPVA is discussed. Using the CPVA differential equation of motion considering gravity, a MATLAB Simulink model is created to simulate the influence of the torque excitation phase on CPVA performance. Especially, one set of CPVA is tested on dynamometer and vehicle, and the test results were compared with simulation results.
Zhang, YiFang, WeirongWu, Guangqiang
NASA asks hard questions: What’s it like on the Moon? Has there been life on Mars? How did the first stars form? Finding these big answers often means first solving a series of smaller but equally vexing questions. For example, how does prolonged weightlessness change the way the brain controls muscles? How does the brain control muscles? Before sending humans on the long journey to Mars, NASA wants to better understand the effects the trip will have on astronauts. Now a company that helped the space agency try to solve these questions is helping others find answers as exciting as any NASA discovery.
Nowadays, the technology war always shows the need for rushing hours in the transportation sector. Turbines and IC engines, which generate power, can only be operated with the help of high-pressure air. In this research, an analytical study introduces an innovative boat vehicle driven by air-water interactions. The principles of an OWC (Oscillating Water Column) wave energy converter device is reviewed to find the effects of air-water interactions that are the key concepts for introducing the partially levitated transportation method. The physical conditions around the boat vehicle, such as squat conditions and speed variations, are reviewed under different stream conditions to explore the possibilities of converting the potential energy of water into kinetic energy under dynamic conditions. An experimental Froude - model analysis is presented to find the velocity and kinetic energy at upstream and downstream conditions of the channel. A 1D analytical method using Matlab is performed to determine the relationship between the gravity, density, and buoyancy forces for the Model. The research work discusses how to apply buoyancy force to the levitation process for the first time, as the buoyancy force acting against gravity can be applied to the levitation process. The buoyancy law is known based on the law of density, and therefore the use of Air is of great importance in this kind of boat vehicle. Since the amount of water determines the buoyancy force, the method of varying the amount of water depending on the given payload with the help of air vessels is discussed. This method is essential as it determines the amount of water required according to the given payload using air vessels when setting up a new waterway. The air vessel pushes water equal to a certain payload out of the boat vehicle, thus, producing waves around the boat vehicle. Furthermore, air vessels simultaneously generate levitation based on the density difference between Air and Water.
Santhiyagu, Arulanantha SamyMayakrishnan, Jaikumar
A person who is inactive for an extended period of time (such as when they have a long illness) loses strength as well as muscle and bone mass. Astronauts on the International Space Station (ISS) face similar risks because bones and muscles begin to atrophy in the absence of gravity. Resistive exercise, where the musculoskeletal system bears weight, has been shown to mitigate these effects. But just lifting weights, as we do on Earth, does not work without gravity.
As NASA develops plans for increasingly ambitious human missions, including a return to the Moon and, eventually, exploration of Mars, more advanced medical risk assessment is necessary in order to keep astronauts healthy. Many aspects of spaceflight can contribute to risk, including altered gravity (which effects blood distribution and vascular biology, muscles, and bones), confinement, changes in sleep patterns, and challenges related to pharmaceutical administration and nutrition. Perhaps the one aspect of the space environment that poses the greatest risk is space radiation. Space radiation consists of energetic protons and helium ions from the sun, as well as galactic cosmic rays — high energy protons and energetic heavy ions — from outside our solar system.
Dragonfly is an X-8 octocopter designed to explore Saturn's moon Titan, and is currently under development for launch in 2026. Titan is a uniquely favorable body for atmospheric flight, in that it has a low gravity (1/7 Earth's) and a dense atmosphere (4x Earth's) which reduce the energetic requirements for heavier-than-air flight. Dragonfly will make multiple (autonomous) flights over several years with ranges of the order of 10km to explore different sites on Titan. The key features of the Titan environment are reviewed. These include the characteristics of the landing site terrain, resembling dune fields in terrestrial deserts. Winds are generally very low, ∼ 1m/s. Stronger winds, and methane rainfall, can occur in rare rainstorms, but these are not expected at the latitude and season of Dragonfly's arrival. Brownout and triboelectric charging due to surface dust lofted by rotor downwash is possible, and these hazards and their mitigations are discussed.
Lorenz, Ralph
Numerical prediction of a confined, co-flowing, laminar jet diffusion flame has been investigated under sinusoidal “g-jitter” to describe the flame structure; this type of flame-body force interaction is typical of a microgravity environment such as in the spacecraft. We introduced g-jitter in the direction orthogonal to the fuel and air inflow. We show that the lower frequencies (0.1-0.5 Hz) of sinusoidal g-jitter significantly affected the flame geometry and behavior. The majority of the flame structure was found to oscillate directly in response to the imposed g-jitter. It has also been observed that nonlinearity in the response behaviors is more prominent in the reaction zone of the flame.
Mondal, Swasti SundarKumar, NavneetGhosh, Pradyumna
It is reasonable to use a two-phase heat transfer loop (TPL) in a thermal control system (TCS) of spacecraft with large heat dissipation. One of the key elements of TPL is a heat-controlled accumulator (HCA). The HCA represents a volume which is filled with vapor and liquid of a single working fluid without bellows. The pressure in a HCA is controlled by the heater. The heat and mass transfer processes in the HCA can proceed with a significant nonequilibrium. This has implications on the regulation of TPL. This article presents a mathematical model of nonequilibrium heat and mass transfer processes in an HCA for microgravity conditions. The model uses the equations of mass and energy conservation separately for the vapor and liquid phases. Interfacial heat and mass transfer is also taken into account. It proposes to use the convective component k for the level of nonequilibrium evaluation. The experiments were carried out in microgravity conditions for the estimation of the k value. The heating of the HCA was investigated in the flight experiments. The working fluid was ammonia. It was determined that in the mathematical model, the k low margin is k = 15…30 for the microgravity conditions. An analysis of the HCA regulation was performed for two values of the k coefficient. It defined that nonequilibrium has a significant impact on the regulation process. It is shown that to ensure a given mode of TPL operation with the HCA equilibrium process (k > 100), a greater HCA heater power is required than in a nonequilibrium process (k = 30).
Gorbenko, Gennadiy OlexandrovichKoval, Polina SergeevnaYepifanov, Konstantin SergeevichGakal, Pavlo GrigorovichTurna, Rustem Yusufovich
Through dynamic computational simulations it is possible to achieve a high reliability index in the development of automotive components, thus reducing the time and cost of the component can generate considerable levels of competitiveness and quality. This work suggests the validation of a methodology to create the virtual routes to find the best design of the flexible components influenced by force of gravity, thermal expansion or even the static balance between the anchor points and used to be designed and installed in the vehicle always in the nominal condition which in many cases diverge from the physical. With the difficulty of predicting mathematically the nonlinear relations of deformation and motion under the effect of forces and moments, we use the NX9 software in the creation of the dynamic movement motion to the motor and transmission assembly imposes on the flexible components through a routine mapped by Cartesian coordinates, simulating the characteristic movements of the vehicle in normal working situations. Using the software IPS - Industrial Path Solution, for the construction of the flexible model to be simulated, the mechanical and geometrical properties were assigned for each component, as well as its static deformation experimentally captured, in order to obtain the real deformations in a steady state, making the virtual static model accurately represent the experimental model validating its effectiveness. Finally, it is established to the model the dynamic routine of some flexible components to make a comparison of the efficiency in the elaboration of routes using the installation by the software IPS meeting the requirements of package, avoiding unwanted dynamic interferences and the early degradation of the flexible element.
Tognolli, AndréUtiyke, FernandoMigliorini, Douglas
This SAE Recommended Practice establishes minimum performance requirements and test procedures for evaluating and testing passenger car side door latch systems. It is limited to tests that can be conducted on uniform test fixtures and equipment in commercially available laboratory test facilities. The test procedures and minimum performance requirements outlined in this document are based on currently available engineering data. It is intended that all portions of the document will be periodically reviewed and revised, as additional knowledge regarding vehicle latch performance under impact conditions is developed.
Motor Vehicle Council
Effect of Using Exhaust Gas Recirculation (EGR) on the Emission Characteristics of the CI Engine Fuelled by Acetone-Butanol-Ethanol (ABE) Diesel Blends2019-01-07484/2/2019
The power generation, agriculture, and transportation sectors are dominated by diesel engines due to better thermal efficiency and durability. Diesel engines are also a major contributor to the air pollutants such as NOx and particulate matter. Acetone-butanol-ethanol (ABE) is considered a promising alternative fuel as it emits less pollutants compared to conventional fuels. In current work, the ABE used was of the ratio (3:6:1) and four samples were prepared for engine trial ABE (10%90%diesel), ABE (20%80%diesel), ABE (30%70%diesel) and ABE (40%60%diesel). Their physio-chemical properties like kinematic viscosity, density, specific gravity and calorific value were checked and tested on compression ignition engine at different operating parameters. The experimental work was conducted upon Kirloskar 4-stroke single cylinder, vertical, air-cooled 661cc compression ignition engine at different speeds and loads. The operational parameters taken were injection temperature, injection pressure and injection timings. The main aim of the current work is to find the effect of exhaust gas recirculation (EGR) on the emission characteristics of acetone-butanol-ethanol (ABE) blends with diesel in compressed ignition engine. Exhaust gas recirculation (EGR) is a promising technology to significantly decrease NOx emissions from diesel engines. The EGR reduces NOx by reducing the oxygen concentration in the combustion chamber, along with this through absorption of heat. The emission characteristics were evaluated using avl gas analyzer and the results were then compared with emission characteristics of ci engine when run with pure diesel
Malhotra, AahanYadav, MukeshTomar, MukulJain, ShikharKumar, Naveen
This SAE Standard defines the requirements for an oil to be used in the SAE HS 806 Oil Filter Test Procedures.
Filter Test Methods Standards Committee
This research deals with the problem of modelling the orbit and attitude motion of uncontrolled manmade objects in orbit about the Earth, which tumble due to the natural influences of the near-Earth space environment. A mathematical, physics-based and computational approach is taken to model the forces and torques that drive the orbit and attitude evolution of such objects. The main influence modelled is solar radiation pressure (SRP), which is the interaction of solar electromagnetic radiation with the surface of an object, leading to both forces and torques that influence the orbital and attitude motion. Other influences, such as the gravitational field of the Earth, are also modelled.
This aerospace recommended practice is applicable to the design of a reusable locking device for cylindrical nuts which are generally tightened with a spanner wrench. Nuts of this type are commonly used to pre-load, and/or position, anti-friction bearings.
E-25 General Standards for Aerospace and Propulsion Systems
This recommended practice covers methods for measuring or evaluating five properties or characteristics of sintered carbide which contribute significantly to the performance of sintered carbide tools. These properties are: hardness, specific gravity, apparent porosity, structure, and grain size. They are covered under separate headings below.
Metals Technical Committee
Experiments of flame-spread of fuel droplets have been performed in microgravity actively. However, the experiment has limitation in the number of droplets due to relatively short microgravity durations in the ground based facilities. It is difficult to conduct flame spread experiments of large scale droplet clouds in microgravity. This study conducted simulation of flame-spread behavior in randomly distributed large-scale droplet clouds by using a percolation approach, in order to make a theoretical link the gap between droplet combustion experiments and spray combustion phenomenon with considering two-droplet interaction. Droplets are arranged at lattice points in 2D lattice. The occurrence probability of group combustion (OPGC) is calculated as a function of the mean droplet spacing (S/d0)m. The (S/d0)m for 0.5 OPGC is defined as the critical mean droplet spacing (S/d0)critical, which separates the droplet cloud into two groups if the lattice size becomes infinity; relatively dense droplet clouds in which the group combustion is excited through flame spread and dilute droplet clouds in which the group combustion in is never excited. The results show that in 2D droplet arrangements, the (S/d0)critical considering two-droplet interaction is higher than that without considering two-droplets interaction.
Saputro, Hermanfitriana, LailaMikami, Masato
It may be possible to generate high power / high frequency gravitational waves (HFGWs) by high frequency accelerated axial rotation (spin) and/or accelerated high frequency vibration of an electrically charged, possibly asymmetric structure, within the context of non-equilibrium thermodynamics, namely far-from-equilibrium physics, highly non-linear in nature. The structure which is the HFGW generator (HFGWG), has the ability to control the accelerated modes of vibration and spin of its electrically charged surfaces, in particular the rapid rates of change of accelerated-decelerated-accelerated vibration and/or accelerated-decelerated-accelerated gyration (axial spin) of these electrified surfaces, in this manner delaying the onset of relaxation to thermodynamic equilibrium, thus generating a physical mechanism which may induce anomalous effects. Under certain conditions, involving rapid acceleration transients, it is observed that there will be exponential growth in electromagnetic energy flux with accelerating vibration. In the present paper, high power HFGWs are generated by enabling the Gertsenshtein effect, that is gravitational wave production by propagating electromagnetic radiation through strong magnetic fields. Controlled motion of charged matter under rapid acceleration transients may enable macroscopic quantum coherence, namely possible quantum mechanical behavior of macroscopic objects. Moreover, the accelerated vibration and/or spin of charged matter may generate high power / high frequency gravitational waves which can be used in a variety of applications, such as advanced field propulsion, namely the design of a workable space drive. Therefore, it may be feasible to propel a hybrid craft equipped with an HFGWG, by producing high frequency gravitational waves which in turn generate their own gravitational fields upon which the craft would propagate in a ‘wave-surfing’ fashion.
Pais, Salvatore Cezar
Items per page:
1 – 50 of 939