An Improved HVQ Algorithm for Compression and Rendering of Space Environment Volume Data with Multi-correlated Variables

Volume visualization can not only illustrate overall distribution but also inner structure and it is an important approach for space environment research.Space environment simulation can produce several correlated variables at the same time.However,existing compressed volume rendering methods only consider reducing the redundant information in a single volume of a specific variable,not dealing with the redundant information among these variables.For space environment volume data with multi-correlated variables,based on the HVQ-1d method we propose a further improved HVQ method by compositing variable-specific levels to reduce the redundant information among these variables.The volume data associated with each variable is divided into disjoint blocks of size 43 initially.The blocks are represented as two levels,a mean level and a detail level.The variable-specific mean levels and detail levels are combined respectively to form a larger global mean level and a larger global detail level.To both global levels,a splitting based on a principal component analysis is applied to compute initial codebooks.Then,LBG algorithm is conducted for codebook refinement and quantization.We further take advantage of progressive rendering based on GPU for real-time interactive visualization.Our method has been tested along with HVQ and HVQ-1d on high-energy proton flux volume data,including>5,>10,>30 and>50 MeV integrated proton flux.The results of our experiments prove that the method proposed in this paper pays the least cost of quality at compression,achieves a higher decompression and rendering speed compared with HVQ and provides satisficed fidelity while ensuring interactive rendering speed.

Nonlinear dynamics of flexible tethered satellite system subject to space environment

The paper studies the nonlinear dynamics of a flexible tethered satellite system subject to space environments, such as the J2 perturbation, the air drag force, the solar pressure, the heating effect, and the orbital eccentricity. The flexible tether is modeled as a series of lumped masses and viscoelastic dampers so that a finite multi- degree-of-freedom nonlinear system is obtained. The stability of equilibrium positions of the nonlinear system is then analyzed via a simplified two-degree-freedom model in an orbital reference frame. In-plane motions of the tethered satellite system are studied numerically, taking the space environments into account. A large number of numerical simulations show that the flexible tethered satellite system displays nonlinear dynamic characteristics, such as bifurcations, quasi-periodic oscillations, and chaotic motions.

The Space Environment Monitors of Shenzhou Manned Spacecrafts

For the purpose of ensuring normal operations of Shenzhou (SZ) series of manned spacecrafts and cosmonauts' safety, Space Environment Monitors (SEM)are mounted on board SZ-2, 3, 4, 5. SEMs aim to detect the high energy particles, the low energy particles, charging potential, atmospheric desity and composition. Detection of SEMs enable us to understand better the space environment in the manned spacecraft's orbit, and to provide a good space environment services for the spacecraft and cosmonauts. In addition, by using the data from SEMs, we have achieved some scientific accomplishments, such as the energy spectra of precipitating electrons, the abnormal variety of atmospheric density and composition during geomagnetic disturbances, the electron angle distribution in the low orbit and so on.

A planetary perspective on Earth's space environment evolution

The planet Earth is an integrated system, in which its multi-spheres are coupled, from the space to the inner core. Whether the space environment in short to long terms has been controlled by the earth's interior process is contentious. In the past several decades,space weather and space climate have been extensively studied based on either observation data measured directly by man-made instruments or ancient data inferred indirectly from some historical medium of past thousands of years. The acquired knowledge greatly helps us to understand the dynamic processes in the space environment of modern Earth, which has a strong magnetic dipole and an oxygen-rich atmosphere. However, no data is available for ancient space weather and climate(>5 ka). Here, we propose to take the advantage of " space-diversity" to build a " generalized planetary space family", to reconcile the ancient space environment evolution of planet Earth from modern observations of other planets in our solar system. Such a method could also in turn give us a valuable insight into other planets' evolution.

Space Environment Measurements and Applications on the Tianhe Core Module of China Space Station

Tianhe Core Module of China Space Station(CSS)equips a set of instruments consisting of a Particle Fluxes and Solar Activity Detector(PFSAD)and two Atmospheric Density Multi-directional Detectors(ADMDs).The PFSAD is to measure X-rays from the Sun and energetic particles in the low-latitude and low altitude regions,including electrons,protons,and helium ions.The ADMDs are to measure thermospheric atmospheric density.The instruments provide real-time data of the orbital space environment,including solar flares,energetic particle variation and thermospheric density enhancement.All the data contribute to the CSS space weather service for mission control and astronaut’s safety.The paper gives preliminary analyses of the space environment measurements from the PFSAD and the ADMDs.By further analysis,the 1024-channel fine spectra of the solar X-ray can be used to study the mechanism of solar flares and their impacts on the Earth’s atmosphere.Data accumulation will be helpful for analyzing mid-term and long-term variations of the South Atlantic Anomaly and atmosphere density.Furthermore,the data are useful to calibrate previous empirical models and establish new models to study the space environment.

Space Environment Prediction for SZ-4 and SZ-5

The Space Environment Prediction Center (SEPC) of the Center for Space Science and Applied Research of the Chinese Academy of Sciences (CSSAR, CAS)took on the mission of offering the space environment parameters which may be of use to the safety of manned spacecraft. In order to complete the space environment safety guarantee mission for SZ-4 and SZ-5, SEPC improved the space environment monitoring system, database system, prediction result display system, prediction implementation system, etc. For guaranteeing the safety of the airship and cosmonaut in the first manned SZ-5, flying experiment mission,SEPC developed the software for analyzing radiation dose and early-warning software for large debris collision with SZ-5. Three months before the flights of SZ-4 and SZ-5, SEPC began to predict the safe launch period in view of the space environment, and offered timely and valid reference opinions for selecting the safety period. Especially during the mission of SZ-5, SEPC analyzed the space high-energy environment in a pre-arranged orbit and abnormal orbit andevaluated the radiation dose which cosmonauts may encounter in space. The evaluation offered an important reference for cosmonaut safety and decisionmaking in the SZ-5 mission. The calculation of the distribution of large debris and the collision risk assessment at different orbit entry times for SZ-5 provided an important base for the superior department to make flight decisions.

China Exported Space Environment Simulator to Russia

In the mid July, 2011, the GVU-600 space environment simulator developed by Bei-jing Institute of Spacecraft Environment Engineering of China Academy of Space Technology (CAST) under China

文献《Validation of commercial fiber optic components for aerospace environments》点评

文章是对一篇SPIE会议文献《用于太空环境的商业光纤器件地面验证方法》的点评。介绍了商业光纤部件从市场采购到准备作为太空飞行部件使用前,在空间环境作用(包括真空、热、振动、辐射)下的地面工艺性合格鉴定试验技术。这项技术由NASA哥达德空间飞行中心(GSFC)创立并命名为"工艺技术有效性保证法",该项技术还包括如何建立商用光纤产品制造工艺性合格鉴定试验验收标准或准则方面的内容。"点评"还针对文献中3个实例之一"水星激光高度仪"试验件的热与振动环境试验规范、试验夹具等重要试验技术信息进行详细介绍。

The influence of space environmental factors on the laser-induced damage thresholds in optical components

This paper systematically investigated the impact mechanisms of proton irradiation,atomic oxygen irradiation and space debris collision,both individually and in combination,on the laser damage threshold and damage evolution characteristics of HfO_(2)/SiO_(2) triple-band high-reflection films and fused silica substrates using a simulated near-Earth space radiation experimental system.For the high-reflection film samples,the damage thresholds decreased by 15.38%,13.12% and 46.80% after proton,atomic oxygen and simulated space debris(penetration) irradiation,respectively.The coupling irradiation of the first two factors resulted in a decrease of 26.93%,while the combined effect of all the three factors led to a reduction of 63.19%.Similarly,the fused silica substrates exhibited the same pattern of laser damage performance degradation.Notably,the study employed high-precision fixed-point in situ measurement techniques to track in detail the microstructural changes,surface roughness and optical-thermal absorption intensity before and after proton and atomic oxygen irradiation at the same location,thus providing a more accurate and comprehensive analysis of the damage mechanisms.In addition,simulations were conducted to quantitatively analyze the transmission trajectories and concentration distribution lines of protons and atomic oxygen incident at specific angles into the target material.The research findings contribute to elucidating the laser damage performance degradation mechanism of transmissive elements in near-Earth space environments and provide technical support for the development of high-damage-threshold optical components resistant to space radiation.

Research on Adaptability Analysis of Environmental Space Demand and Design Optimization of Daycare Centers: Taking Chongqing’s Community F as an Example

Currently,there is a lack of research on the detailed environmental spatial design of community daycare centers at the micro level.This study focuses on Community F in Chongqing,using the elderly’s“willingness to demand”as a central aspect.It examines indoor and outdoor environmental space needs at a micro level,considering both functional requirements and spiritual needs based on existing research.The analysis incorporates three adaptive elements:current construction,surrounding environment,and operational management.It explores the feasibility of restructuring spatial layouts,utilizing local resources,and integrating Bayu cultural characteristics.Finally,through design optimization practices,the study proposes three strategies for aging optimization:functional integration and interaction,user-friendly facilities,and emotional connections to place.

Application of MoS_(2)in the space environment:a review

A considerable portion of space mechanism failures are related to space tribological problems.Cold welding in high vacuum;surface erosion and collision damage caused by various radiations,high temperature oxidation under atomic oxygen(AO)bombardment;and thermal stress caused by temperature alternation all alter the physical,chemical,and friction properties of materials.In particular,the space vibration caused by alternating temperatures and microgravity environments can alter the motion of the contact body,further affecting its friction properties.Improving the friction properties of contact surfaces in the space environment is an important way to extend the service life of spacecraft.Traditional lubricants can no longer meet the lubrication requirements of the space environment.This study describes the characteristics of the space environment and the applications of solid lubricants.The friction properties of MoS_(2),a solid lubricant widely used in space,are discussed.The synergistic lubrication of MoS_(2)with surface textures or metals is presented.Advances in research on the friction properties of collision sliding contacts in the space environment are reviewed.The combination of MoS_(2)and soft metals with surface textures is introduced to reduce the effects of vibration environments on the friction properties of moving parts in space mechanisms.Finally,the challenges and future research interests of MoS_(2)films in space tribology are presented.

The space environment monitor aboard FY-2 satellite

The space environment monitor(SEM)aboard FY-2 satellite consists of the high energy particle detector(HEPD)and the solar X-ray flux detector(SXFD).The SEM can provide real-time monitoring of flare and solar proton event for its operation at geostationary orbit and is also the first Chinese space system for monitoring and alerting solar proton event.During the 23rd solar maximum cycle,almost all the solar proton events that took place in this period are monitored and some of them are predicted successfully by analyzing the characteristics of X-ray flare monitored by the SEM.Some basic variation characteristics of particle at geostationary orbit are found such as day-night periodic variation of particle flux,the electron flux with energy>1.4 MeV in the scope from 10 to 200/cm^(2).s-sr and the proton flux with energy>1.1 MeV in the scope from 600 to 8000/cm^(2)-s.sr during the time with no magnetic storm and solar eruption.

Diversity and Stability Study on Rice Mutants Induced in Space Environment

To further study the characteristics of changes on the molecular level of rice mutants induced in space environment, we analyzed proteins in leaves and seeds of four rice mutants （two high-tillering and two low-tillering） in the 8th and 9th generations after a 15-day spaceflight, and compared with their ground controls by two-dimentional polyacrylamide gel electrophoresis and reverse phase liquid chromatography （RPLC）. In addition, the albumin, globulin, prolamine, glutelin, and amylose of the mutant seeds were analyzed by RPLC and ultra-violet spectrometry. The results showed that the low-abundance proteins of leaves in the peak tillering stage are more likely to he induced compared with their corresponding controls. The albumin, globulin, and prolamine of the mutant seeds revealed changes when compared with their controls, and the characteristics of changes in different mu- tants were stably inherited in the 8th and 9th generations, suggesting that they can be used as biomarkers to identity the mutants induced by spaceflight. Moreover, two proteins （SSP9111 and SSP6302） were found to be expressed with high intensity （two-fold change） in different mutants, which were both correlated with photosystem according to mass spectrometry and database searching.

Space luminous environment adaptability of missile-borne star sensor

To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky, a study on space luminous environment adaptability of missile-borne star sensor was carried out. By Plank blackbody radiation law and some astronomic knowledge, irradiancies of the stray at the star sensor working height were estimated. By relative astrophysical and mathematics knowledge, included angles between the star sensor optical axis point and the stray at any moment were calculated. The calculation correctness was verified with the star map software of Stellarium. By combining the upper analysis with the baffle suppression effect, a real-time model for space luminous environment of missile-borne star sensor was proposed. By signal-noise rate （SNR） criterion, the adaptability of missile-borne star sensor to space luminous environment was studied. As an example, a certain type of star sensor was considered when imaging to the starry sky on June 22, 2011 （the Summer Solstice） and September 20, 2011 （August 23 of the lunar year, last quarter moon） in Beijing. The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height. In each period of time, the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index. When the included angle is larger than the shielded angle and less than 90~, the stray is restrained by the baffle. The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface. When the irradiancy of 6 magnitude star is 5 times more than that of the stray, there is no effect on the star point target identification. The simulation results are identicat with the actual situation. The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model. The adaptability of the star sensor to space luminous environment can be analyzed conveniently. A basis for determining the relative star sensor indexes, the navigation star chosen strategy and the missile launch window can be provided.

A Hygienic Survey of the Environment of Underground Space and Buildings

Full utilization of underground space and buildings could have positive economic and social effects. However, the microclimate and air quality must be well controlled so that they are not harmful to human health. This survey indicated that relative humidity is a common hygienic problem in underground space and buildings. Attention should be paid to humidity control and to the strengthening of routine ventilation at the construction stage. Carbon dioxide can be used as a hygiene index of air pollution; the sanitary standard for it in the air of underground buildings is 10%. The hygienic survey shows that the concentration of carbon dioxide is usually below this standard in the environments of underground space and buildings. (c)1989 Academic Press,Inc.

Analysis of the Impact of Large Constellations on the Space Debris Environment and Countermeasures

Large constellations have developed rapidly in recent years because of their unique advantages, but they will inevitably have a major negative impact on the space debris environment, leading to its deterioration. The key to mitigate the impact is the success rate and duration of the post-mission disposal(PMD) process. Aiming at solving this problem, this paper further studies the impact of large constellations on other space assets under different PMD strategies through simulation, and proposes corresponding strategies and suggestions for mitigation.According to One Web’s large constellation launch plan, the dangerous intersection of the large constellation with existing space assets at different stages of the constellations life cycle is calculated by simulation. Based on this, the influence of the large constellation operation on existing space assets at different times and strategies of PMD is analyzed. The conclusion shows that in the PMD stage, large constellations have the greatest impact on existing space assets;the PMD duration and number of satellites performing PMD at the same time are key factors to the degree of negative impact. The faster the PMD is, the less threat it poses to other spacecraft. More results and conclusions are still being analyzed.

Physical properties of relativistic electron beam during long-range propagation in space plasma environment

It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment.Most prior studies discussed the focusing characteristics of the beam in the ion channel,but the establishment process and transient properties of the ion channel itself,which also plays a crucial role during the propagation of the relativistic electron beam in the plasma environment,were commonly neglected.In this study,a series of two-dimensional(2D)particle-in-cell simulations is performed and an analytical model of ion channel oscillation is constructed according to the single-particle motion.The results showed that when the beam density is higher than the density of plasma environment,ion channel can be established and always continues to oscillate periodically over the entire propagation.Multiple factors,including the beam electron density,initial beam radius,and the plasma density can affect the oscillation properties of ion channel.Axial velocity of the beam oscillates synchronously with the ion channel and this phenomenon will finally develop into a two-stream instability which can seriously affect the effective transport for relativistic electron beam.Choosing appropriate beam parameters based on various plasma environments may contribute to the improvement of the stability of ion channel.Additionally,radial expansion of the beam can be limited by ion channel and a stable long-range propagation in terrestrial atmosphere may be achieved.

Commodification of Traditional Open Spaces as a Commodity and the Consequent Damage of Environmental Ethics (Case Study in Ubud Village Bali Indonesia)

This paper aims to examine the phenomenon of commodification of traditional open space into commodities which results in the destruction of environmental ethics. Environmental ethics places restrictions on freedom in exercising ownership rights and pays more attention to ethical obligations to the environment. The anthropocentric approach should be avoided because it only sees the environment from its commercial angles to satisfy human interests. This research critically describes the reality of the utilization of traditional open spaces in Ubud to become an economic space. The rapid influence of global culture has implications for the practices of capitalist culture within the frame of the tourism industry, resulting in cultural industries, popular culture, hedonic lifestyles and consumerism. This study used a qualitative method. The data was obtained through observation, interviews, literature studies, and documents. The results of the study revealed how traditional open spaces were produced, distributed and consumed by the market. Traditional open spaces were commercialized, traded like goods and services. Traditional open spaces, such as paddy fields, cliffs, telajakan (front part of the house complex), city parks, domestic properties, backyards, cemeteries have been turned into economic spaces to satisfy the taste of tourists. Space is controlled and commodified by capital owners to feed their economic libido while disobeying environmental ethics.

Environmental Design of Urban Outdoor Public Spaces Based on Children's Activities

This paper analyzed current situation of domestic and foreign children's outdoor spaces, and the relationship between urban public spaces and children's behaviors, summarized design principles and techniques to improve use efficiency of urban outdoor public spaces and facilities, create public spaces capable of meeting psychological behavior needs of children.

Urbanization and Its Impacts to Food Systems and Environmental Sustainability in Urban Space: Evidence from Urban Agriculture Livelihoods in Dar es Salaam, Tanzania

Urbanisation is the key factor underpinning and catalysing changes in food systems, environmental quality, climate change and agriculture livelihoods in the overall urban ecosystem setting and its sustainability. The paper explores Dar es Salaam, a rapidly expanding city in Sub-Saharan Africa, and shows that urban agriculture provides urban ecosystem services and contributes to environmental sustainability. The interconnections of environmental justice, urban ecosystem services and climate change and variability found eminent feature that influence land governance, productivity and aesthetic value of the city. The study reaffirms the pivotal role urban agriculture which plays to enhance community health services and access to resources, with important implications on urban environmental sustainability and redistributive spatial land use planning policies and practices. The process of urbanisation, forms of urban agriculture and government strategies for enhanced urban food systems in the city economy have been highlighted. Equally, the process triggers the transformation of settlements from rural in character to modernity with an augmented land use conflicts. The results suggests that with increasing population, a clear spatial land use planning and management strategy is required to overcome the challenges and enhanced food systems and urban environmental sustainability in rapidly urbanizing cities like Dar es Salaam in Sub-Saharan Africa.