基于H∞理论的磁流变阻尼器半主动容错控制

建筑结构的半主动控制系统中的传感器,在强震作用下可能因出现故障而影响控制效果。以磁流变阻尼器为例,研究半主动容错控制系统的设计方法。首先,研究了基于状态观测器的半主动H∞控制器设计方法,并将之应用到建筑结构采用磁流变阻尼器的减振控制中;运用改进Bouc-Wen模型,计算磁流变阻尼器的阻尼力,通过求解一个代数Riccati方程和一个状态观测方程,得出了基于状态观测器的H∞主动控制律;再对其采用Clipped-optimal方法实施半主动控制策略。然后,针对传感器故障,利用观测器组的输出残差对故障进行在线诊断,并通过几个观测器状态值的比较得到故障的大小,并据此对传感器的测量值进行修正,从而消除故障对闭环系统的影响,最终实现半主动H∞容错控制。仿真结果表明,该方法具有很好的容错控制效果。     

Effects of excited-state structures and properties on photochemical degradation of polybrominated diphenyl ethers: a TDDFT study

This study presents new insight into the photochemical degradation of polybrominated diphenyl ethers (PBDEs), and it provides details about the structures and properties of 27 PBDE congeners in the electronically excited state using the time-dependent density functional theory method. Each PBDE congener exhibited remarkably different geometries in the ground state and the excited state. The significant lengthening of C-Br bond in each PBDE congener was observed in the excited state for the first time by theoretical calculation, which is directly involved in the photochemistry reductive debromination of n-BDE to (n−1)-BDE. Generally, the lengthening of C-Br bonds cannot occur at the para position. Furthermore, the calculated results demonstrated that the photoreactivity of PBDEs increased with an increase of bromination degree. It was also found that the pattern of Br substituents had an effect upon the photoreactivity of PBDEs. These findings suggest that the information obtained in the excited state is crucial to the mechanism explanation of the photochemical degradation of PBDEs.     

Use of fungi for the bioconversion of rice straw into cellulase enzyme

Cellulase production was carried out by solid state bioconversion (SSB) method using rice straw, a lignocellulosic material and agricultural waste, as the substrate of three Trichoderma spp. and Phanerochaete chrysosporium in lab-scale experiments. The results were compared to select the best fungi among them for the production of cellulase. Phanerochaete chrysosporium was found to be the best among these species of fungi, which produced the highest cellulase enzyme of 1.43 IU/mL of filter paper activity (FPase) and 2.40 IU/mL of carboxymethylcellulose activity (CMCase). The “glucosamine” and “reducing sugar” parameters were observed to evaluate the growth and substrate utilization in the experiments. In the case of Phanerochaete Chrysosporium, the highest glucosamine concentration was 1.60 g/L and a high concentration of the release of reducing sugar was measured as 2.58 g/L obtained on the 4th day of fermentation. The pH values were also recorded. The range of the pH was about 5.15 to 5.56 in the case of Phanerochaete Chrysosporium.     

改性纤维素吸附剂的合成及其对铜离子的吸附

建立了一种简单方便的纤维素改性的固相合成方法。采用普遍廉价的滤纸作为原料,用固相合成法将预处理后的滤纸纤维经琥珀酸酐进行酯化改性,制备成新型的纤维素吸附剂,通过质量增比、扫描电镜、傅里叶红外光谱仪和X射线衍射仪对制备的吸附剂进行了分析表征,并且探究了离子初始浓度、溶液p H和吸附时间对改性纤维素吸附铜离子的影响。结果表明,在室温下初始离子浓度为1 000 mg/L,离子溶液体积为50 m L,加入0.1 g纤维改性剂,p H为4.0~5.0,吸附平衡时间为50 min时,滤纸纤维改性后最大吸附铜离子质量可达470 mg/g,铜离子去除率达到94%。     

The environmental state as a model for the world? An analysis of policy repertoires in 37 countries

Scholars have proposed the analytical concept of the environmental state, a state where government actively addresses negative environmental externalities of economic activities. The mapping of environmental regulatory expansion in Western countries has been central in recent attempts to identify the environmental state empirically. Surprisingly little is known, however, when it comes to the environmental regulatory expansions in non-Western countries. Are there similar trends towards the emergence of environmental states in the non-West as well? From analysing data covering 25 policies in 37 countries, it appears that regulatory expansion has also occurred in the non-Western world, and the distinction between the West and the non-West has been reduced over time. There are non-Western countries among environmental pioneers, and there is some evidence for the trend of global convergence. Future research on environmental states should take into account emerging environmental states in the non-West.     

The indecisive role of the market in China’s SO2 and COD emissions trading

Governmental intervention is essential to combat environmental pollution, a phenomenon classically explained as market failure, while market-based environmental policy instruments have provided cost-effective alternatives. By examining five pilot air pollution (sulfur dioxide) and water pollution (chemical oxygen demand) trading schemes in China through a market-based theoretical framework and extensive empirical analysis, this research analyzes where a state-market boundary is defined, whether the market is performing effectively, and, critically, what leads to underperformance. Constrained by policy design, policy conflicts, and excessive state intervention, the market has not played an effective and ‘decisive’ role, resulting in low market thickness for participants and transactions, market congestion on prices, and inadequate market safety for genuine emissions trading. Better emissions trading for conventional pollutants and CO₂ requires better market-oriented rules, improved policy coordination, and stronger implementation while minimizing state intervention.     

The four faces of the environmental state: environmental governance regimes in 28 countries

The primary task for the environmental state is to address problems related to the market’s externalisation of environmental costs. It has four main resources at its disposal: regulation, redistribution, organisation, and knowledge generation. The way these four resources are deployed make up a state’s environmental governance arrangements. Using data on environmental regulation, taxes, public administrations, and knowledge production from 28 countries, and a hierarchical cluster analysis, four different types of environmental states are identified: established, emerging, partial, and weak. This is followed by some suggestions for further research on the environmental state in a comparative perspective.     

Remedies for loss and damage caused by climate change from the dimension of climate justice

Adverse consequences to the ecological system and human health caused by impacts potentially attributable to climate change have already drawn great and widespread concern of many scientists and international organizations. However, we still have a hard time determining exactly the impact of climate change on the environment or the damage that climate change inflicts on countries comprising small islands or low-lying lands in light of today’s science and technology. The progress for dealing with the issue of loss and damage has been struggling for a long time from the beginning to the present. In this paper, the author begins by summarizing talks on the concept and the positions of commentators. The author is proposing that the development of future climate negotiations and rule-making process be based on global climate justice as a standard for measuring value. Also, the author proposes that a holistic view of climate justice be established. Generally, three aspects of climate justice can be derived. First, the dimension of human rights protection shows that protection of fundamental human rights is a logical precondition if small-island and low-lying countries are able to achieve climate justice. Second, the definite and traditional concepts of distributive justice and corrective justice hold the view that the principle of common but differentiated responsibilities should be upheld as a basic standard of allocating rights and duties associated with climate change. Third, climate justice requires that any state follow the “no-harm principle,” which is regarded as an international customary rule. According to the principle, the obligation of states to prevent the use of their territory for causing trans-boundary harm to the environment shall be a violation of state responsibility, which incurs international punishment. Then we put forward three remedial approaches in light of climate justice, including the approach of State Responsibility (SR) based on the principles and rules of international human rights law and international environmental law. Based on clear rules, the judge can determine whether the damaging behavior or the damage perpetrated by a state party constitutes a state responsibility. The International Environmental Regulation (IEB), which means solving the problems within the framework established by the Conventions on Climate Change, takes advantage of the market mechanisms and incentives such as fund and insurance support system to relieve or compensate the loss and damage. International Environmental Dispute Settlement Mechanism (IEDSM), which includes the means such as consultations, negotiations, nonmandatory ways and international arbitration, international judicial ways to solve these disputes, functions as a procedural safeguard. As an active promoter of global climate governance, China should no doubt stand by the principle of Common But Differentiated Responsibility (CBDR) and take it as a basis for negotiations, actively strengthen the work of South-South cooperation, fulfill her international climate commitments without reservation, vigorously develop a low-carbon economy, and actively promote international negotiations on the subject of loss and damage.     

Growth and photosynthetic responses to copper in wild grapevine

The present study evaluates the tolerance and accumulation potential of Vitis vinifera ssp. sylvestris under moderate and high external Cu levels. A greenhouse experiment was conducted in order to investigate the effects of a range of external Cu concentrations (0–23 mmol L⁻¹) on growth and photosynthetic performance by measuring gas exchange, chlorophyll fluorescence parameters and photosynthetic pigments. We also measured the total copper, nitrogen, phosphorus, sulphur, calcium, magnesium, iron, potassium and sodium concentrations in the plant tissues. All the experimental plants survived even with external Cu concentrations as high as 23 mmol L⁻¹ (1500 mg Cu L⁻¹), although the excess of metal resulted in a biomass reduction of 35%. The effects of Cu on growth were linked to a reduction in net photosynthesis, which may be related to the effect of the high concentration of the metal on photosynthetic electron transport. V. vinifera ssp. sylvestris survived with leaf Cu concentrations as high as 80 mg kg⁻¹ DW and growth parameters were unaffected by leaf tissue concentrations of 35 mg Cu kg⁻¹ DW. The results of our study indicate that plants of V. vinifera ssp. sylvestris from the studied population are more tolerant to Cu than the commercial varieties of grapevine that have been studied in the literature, and could constitute a basis for the genetic improvement of Cu tolerance in grapevine.     

Cyclo-stationary maximum cross-covariance analysis for exogenously forced environmental systems

The response of an ecological system to external forcings shows marked seasonality and complex time delays. In order to take seasonality into account, the assumption of stationarity inherent in most statistical models for time series is replaced here by more flexible cyclo-stationarity. To describe the dominant modes of the cross-covariance structure of the system and the forcing, temporal (orthonormal) patterns are derived. They are estimated by a singular value decomposition of the cyclo-stationary sample cross-covariance matrix. These patterns allow to formulate a prediction scheme for the system once the forcing is known. The method has comparatively little tendency for multi-collinearity, so that it is well applicable also for multivariate settings and shorter data records. The method is illustrated for an aquatic ecosystem with distinct phases of a biological succession.