Experimental study on the space charge properties in haze events

In recent years, haze has posed a serious threat to the global climate change, ecological balance and human health. In this study, the laboratory experiments and field observations were performed and a possible charging mechanism was proposed to investigate the space charge properties in haze events. The laboratory experiments showed that the charge polarity of primary aerosol is determined by species of combustion fuels while the magnitude is dependent on the combustion completeness. The field observations revealed that the space charge of atmosphere aerosol in haze events differs from that of fair weather and is closely related to PM_2.5 concentration when Relative Humidity (RH)?<?60%, with 1 to 2 orders of magnitude less than the case when RH?≥?60%. The analysis of equivalent charge-to-mass ratio (ECTM) suggested that in haze events the space charge is governed by primary aerosol emitted by combustion of fossil fuel in a low relative humidity, whereas it is manipulated by the secondary chemical reaction of atmosphere aerosol in a high relative humidity. And we can identify the main pollutants in haze events according to the polarity of atmosphere aerosol and quickly take measures when RH?<?60%. Accordingly, the dust-haze of RH?<?80% can be divided into dry-dust-haze when RH?<?60% and wet-dust-haze when 60%?≤?RH?<?80%. Our study firstly elucidated the space charge properties of atmosphere aerosol in haze events and can provide a new perspective for the prevention and control of air pollution.     

The riddle of “life,” a biologist’s critical view

To approach the question of what life is, we first have to state that life exists exclusively as the "being-alive" of discrete spatio-temporal entities. The simplest "unit" that can legitimately be considered to be alive is an intact prokaryotic cell as a whole. In this review, I discuss critically various aspects of the nature and singularity of living beings from the biologist's point of view. In spite of the enormous richness of forms and performances in the biotic realm, there is a considerable uniformity in the chemical "machinery of life," which powers all organisms. Life represents a dynamic state; it is performance of a system of singular kind: "life-as-action" approach. All "life-as-things" hypotheses are wrong from the beginning. Life is conditioned by certain substances but not defined by them. Living systems are endowed with a power to maintain their inherent functional order (organization) permanently against disruptive influences. The term organization inherently involves the aspect of functionality, the teleonomic, purposeful cooperation of structural and functional elements. Structures in turn require information for their specification, and information presupposes a source. This source is constituted in living systems by the nucleic acids. Organisms are unique in having a capacity to use, maintain, and replicate internal information, which yields the basis for their specific organization in its perpetuation. The existence of a genome is a necessary condition for life and one of the absolute differences between living and non-living matter. Organization includes both what makes life possible and what is determined by it. It is not something "implanted" into the living beings but has its origin and capacity for maintenance within the system itself. It is the essence of life. The property of being alive we can consider as an emergent property of cells that corresponds to a certain level of self-maintained complex order or organization.     

Electrostatic ignition of sensitive flammable mixtures: Is charge generation due to bubble bursting in aqueous solutions a credible hazard?

Experiments have been conducted to gain insight into the credibility of sparging aqueous solutions as an electrostatic ignition hazard for sensitive hydrogen/air or fuel/oxygen mixtures (Minimum Ignition Energies of ∼0.017 mJ and ∼0.002 mJ, respectively, compared to ∼0.25 mJ for hydrocarbon/air mixtures). Tests performed in a 0.5 m³ ullage produced electric field strengths between 125 and 560 V m⁻¹ for air flows of 5–60 l min⁻¹, respectively, comprised of 2–4 mm diameter bubbles. Field strength can be related to the space charge and fitting to an exponential accumulation curve enabled the charge generation rate from the air flows to be estimated. This was observed to be directly proportional to the air flow and its magnitude was consistent with literature data for bubble bursts. The charge accumulation observed at laboratory scale would not be a cause for concern. On the basis of a simple model, the charge accumulation in a 27 m³ ullage was predicted for a range of air flows. It is apparent from such calculations that ignition of hydrocarbon/air mixtures would not be expected. However, it would seem possible that field strengths might be sufficient to cause a risk of incendive spark or corona discharges in moderately sized vessels with sensitive flammable mixtures.     

钢结构暨空间结构的抗火设计综述

钢结构暨空间结构是目前建筑结构的重要发展方向之一。因钢材对高温的敏感性 ,其防火、抗火性能的研究应是设计时考虑的重要因素。笔者简述了抗火与防火的概念及其区别 ;评估了国内外关于抗火设计的基本方法及优缺点 ;重点对整体结构有限元非线性抗火反应全过程分析方法进行了讨论。通过选择科学的抗火设计方法 ,将为经济、适用的防火设计提供重要的依据     

载人航天空间环境模拟试验安全与措施

载人航天空间环境模拟试验极其危险 ,为了确保参试航天员的生命安全 ,必须对模拟试验设备进行系统配套与完善 ,同时必须事先进行人员培训、制定详细的试验流程 ,进行严密的组织管理。为此 ,重点介绍了为确保参试航天员的安全 ,对试验设备所提出的技术要求 ,以及试验所涉及的训练、演习、试验组织管理等方面的安全措施。     

Evaluation of the European Space Agency Climate Change Initiative Soil Moisture Product over China Using Variance Reduction Factor

In this study, we evaluated the European Space Agency Climate Change Initiative soil moisture product v02.1 (ESA CCI SM v02.1) using in situ observations collected at 547 stations in China from 1991 to 2013. A conventional validation was first conducted, and the triple collocation errors of ESA CCI SM and the European Centre for Medium Range Weather Forecasting reanalysis data were approximately 0.053 and 0.050 m³/m³, respectively. To obtain more reliable validation results, the average soil moisture of the in situ observations per ESA CCI SM pixel was also used as the validation sites. Variance reduction factor (VRF) was adopted to quantify the accuracy of the soil moisture validation sites, and the average VRF was estimated at 4.88%. The validation results were enhanced by excluding validation sites with VRF errors greater than 5% from the statistical analysis. Although the ESA CCI SM underestimated the in situ observations with a Bias of 0.05 m³/m³, a moderately high correlation coefficient of 0.44 and a relatively small unbiased root‐mean‐square difference of 0.05 m³/m³ were observed. This study provides information on the utilization of ESA CCI SM for ecological protection, climate change, and hydrological forecasting. It also suggests the adoption of VRF for future error corrections of satellite‐based products.     

Human performance in polar environments

An overview of the physical, psychological, social, and coping aspects of living and working in polar regions is presented, assessing findings from both expedition teams and work groups. A personal narrative describing the experiences of a polar expeditioner is interspersed in relevant sections to provide a deeper understanding of the challenges of performing in an extreme environment. The application of findings from polar environments as an analog for space missions is discussed. We conclude that further research is needed on the integration of psychosocial and neurobehavioral adaptation. Furthermore, it is important to consider both the positive as well as negative features of living and working in polar and other extreme environments, and develop training strategies and countermeasure tools to optimize performance in these conditions.     

Quality standard codes of reference of Jordanian coastal waters of the Gulf of Aqaba, Red Sea

Back in 1992, the Gulf of Aqaba Environmental Action Plan (GAEAP), a collaboration between the Aqaba Region Authority (ARA), Jordan and the World Bank, gave considerable emphasis to the environmental protection of the Gulf of Aqaba [The World Bank. Gulf of Aqaba Environmental Action Plan. Report No. 12244JO (1993).]. The document recommended the establishment of a marine reserve and the long term monitoring of the coastal habitats' environmental quality. The combination of a dedicated follow up, the collaborative efforts of ARA and the Marine Science Station (MSS), and the founding of the Aqaba Special Economic Zone Authority (ASEZA) have turned the recommendations into reality. A comprehensive monitoring program of the Jordanian coastal habitats commenced in 1999. The first three years of the program were financed by a donation from The Global Environmental Facility (GEF). In return, Jordan has committed itself to the maintenance of the monitoring program as an ongoing tool for sustainable coastal management. The monitoring program includes observations on benthic habitat, fish communities, bottom sediments and seawater quality. This paper focuses on the results of seawater-quality monitoring in the first three years. Records of weather conditions, coastal currents, seawater temperature, transparency, salinity, density, pH, alkalinity, dissolved oxygen, ammonia, nitrate, nitrite, phosphate, silicate, particulate matter, chlorophyll a, zooplankton biomass, total coliform, fecal coliform, hydrocarbons and sedimentation rate have been generated monthly since January 1999 at six coastal stations, and one offshore reference station, in the Jordanian waters of the Gulf of Aqaba. The coastal stations are located at sites with different benthic habitats and are occupied by different human activities. Offshore records of density (thermohaline structure), nutrients and chlorophyll a depicted two well-defined seasons; a nutrient-/chlorophyll a-rich, mixed water winter from December to April and a nutrient-/chlorophyll a-poor, stratified water summer from June to October. Short transition seasons appeared in May and November. The mixing and stratification seasons were also clearly depicted in the coastal waters. Statistical analysis of the three-year data collected at the offshore station revealed no significant inter-annual differences in the upper 125 m of the water column with respect to any of the measured parameters. At coastal stations, the water quality at the two northernmost stations was significantly different in comparison to the upper 125 m at the offshore station and to the other coastal stations, with respect to the two key indicator parameters: inorganic nitrogen and chlorophyll a. The three-year findings of the monitoring program are employed to suggest standard codes of reference for the coastal water quality.     

我国环境空间规划制度的研究进展

建立严格的环境空间管控制度,可以破解现阶段城市出现的一系列复合型、区域性和格局性环境问题,对从源头促进"人-城市-自然"和谐发展具有重要意义。为全面梳理环境空间规划制度和弥补其研究发展中的不足,对以环境功能区划、城市环境总体规划和生态保护红线制度为代表的环境空间规划制度的理论、技术与实践进行了较为全面的分析,对现有研究和未来探索提出展望,以期为以环境质量改善和风险防范为指导的环境空间规划制度提供理论依据和实践管理经验,从而全面引导城市的健康可持续发展。     

论空间规划的“三个空间”与“两个边界”

通过梳理与总结各类具有空间性质的规划中提及的管控空间类型,分析了各类空间性规划在制度与实践中存在的问题,对空间规划的重点内容即生产空间、生态空间、生活空间以及保护边界和开发边界的对象进行了初步划分,并且对"三个空间"和"两个边界"的特征进行了初步归纳。