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This paper aims to study the oscillation phenomenon before chaos as well as its mechanism of occurrence in the energy-saving and emission-reduction system.

The system dynamics analysis, phase portrait analyses, equilibrium point analysis and bifurcation curve were applied to this paper.

First, the authors find an oscillation phenomenon previous to chaos. Second, on the one hand, the existence of two unstable saddles is the reason for the occurrence of oscillation phenomenon. On the other hand, the increasing of carbon emissions can arouse oscillation phenomenon.

This paper finds an oscillation phenomenon previous to chaos in the energy-saving and emission-reduction system. The mechanism of occurrence of oscillation phenomenon is studied. The existence of two unstable saddles is the reason for the occurrence of such oscillation phenomenon. The oscillation is related with fold bifurcation. The study also provides a theoretical basis for the further study of chaos control.

Distribution and occurrence of aromatic compounds and elements in the coal gangue dump from Fengfeng Coal Mine 5 and their influences on the environments have been studied in this paper. The samples were taken from the coal gangue dump, coal waste water stream and soil surface samples. These samples were analyzed by organic and inorganic methods. The results indicate that the coal gangues contain abundant harmful substances like aromatic hydrocarbon compounds, sulfur and trace elements. These harmful substances have influenced around area. In the soil surface, they influence the environments at least 750 m far from the coal gangue dump. In the waste water stream, they influence the water quality at least 2500 m far from the coal gangue dump.

The purpose of this paper is to describe the current status of open access (OA) in China, including problems and possible solutions and to introduce the role of the academic library in OA.

This research paper analyzes several successful OA projects with a focus on the user requirements and the role of the academic library. The paper also analyzes the current status of OA in three areas. First, publishers. The paper will introduce some Chinese OA websites in detail, and point out the problems facing Chinese OA. Second, OA users (both writers and readers) requirements will be investigated. Third, the role of libraries will be analyzed.

The libraries goal of sharing resources is similar to that of the OA movement. The paper will recommend some Chinese OA resources set up by libraries. The paper will also describe OA promotion by China libraries. Some suggestions for the way forward are also described.

The paper will analyze OA development and problems in China from a librarian perspective. The paper does not have a deep understanding of the publishing business. Most of the best Chinese academic papers are published in foreign commercial academic journals, which costs Chinese writers their intellectual property rights since their rights of communication through the internet is then owned by foreign publishers. As a result, most products based on public investment in China become a foreign publisher's exclusive property, earning exclusive profit for them rather than for China. This situation exists not only in China, but also in other developing countries. This “problem” is worth researching.

A comprehensive introduction to the current state of OA in China will be useful to those who are unfamiliar with, or seek deeper knowledge of, the Chinese situation. The constructive suggestions to be offered should be useful to Chinese administrators, OA publishers and librarians.

This may be the first research paper describing the status of OA in China in summary and in detail, with an analysis of the problems in OA development and offering recommendations.

The purpose of this paper is to develop multilayer clothing assemblies consisting of fibrous battings and reflective nano-fibrous thin layers for cold protective clothing for improved thermal insulation.

Thermal insulation values of totally 20 assemblies made of varying layers of a thick polyester batting and four different types of thin interlayers were measured using a guarded hot-plate to investigate the effect of the properties of thin interlayers and construction of multilayer assemblies on thermal insulation. Cold protective jackets filled with polyester battings sandwiched with or without interlayers were also made and tested on the sweating fabric manikin-Walter.

Results show that the Rosseland mean extinction coefficients of the thin interlayer and the associated radiative thermal conductivity of the interlayers have significant influence on thermal insulation of the assembly when more than one reflective nano-fibrous interlayers are sandwiched in the assembly. The cold protective jacket filled with multilayer polyester battings and reflective nano-fibrous interlayers have better thermal insulation and moisture permeability index (i_m) than those filled with the same multilayer polyester battings, but with non-reflective nonwoven interlayers or without interlayers.

This paper clearly demonstrates the advantages of reflective nano-fibrous thin material for interlayers in the cold projective jacket.

The ecological environment of the Loess Plateau, China, is extremely fragile under the context of global warming. Over the past two decades, the vegetation of the Loess Plateau has undergone great changes. This paper aims to clarify the response mechanisms of vegetation to climate change, to provide support for the restoration and environmental treatment of vegetation on the Loess Plateau.

The Savitsky–Golay (S-G) filtering algorithm was used to reconstruct time series of moderate resolution imaging spectroradiometer (MODIS) 13A2 data. Combined with trend analysis and partial correlation analysis, the influence of climate change on the phenology and enhanced vegetation index (EVI) during the growing season was described.

The S-G filtering algorithm is suitable for EVI reconstruction of the Loess Plateau. The date of start of growing season was found to gradually later along the Southeast–Northwest direction, whereas the date of the end of the growing season showed the opposite pattern and the length of the growing season gradually shortened. Vegetation EVI values decreased gradually from Southeast to Northwest. Vegetation changed significantly and showed clear differentiation according to different topographic factors. Vegetation correlated positively with precipitation from April to July and with temperature from August to November.

This study provides technical support for ecological environmental assessment, restoration of regional vegetation coverage and environmental governance of the Loess Plateau over the past two decades. It also provides theoretical support for the prediction model of vegetation phenology changes based on remote sensing data.

The purpose of this paper is to present some new results about reflective cold protective clothing (i.e. those featuring metal coatings), and compare and contrast the data with other recent research work.

The authors used a thermal manikin and a guarded hot plate to determine the thermal resistance of different textile assemblies and garment featuring plasma-deposited metal-coated insulation and interlayers.

Depending on the exact approach, the authors show that metal coatings can increase the thermal resistance of textile assemblies by ∼30-75 per cent.

New data on reflective cold weather clothing show that metal coatings could be an important addition to cold weather clothing, especially those featuring high air permeability/optical porosity insulation. Plasma-deposited metal coatings cause the lowest increase in weight.

This paper provides new data about the efficacy, in terms of thermal resistance, of metal coatings for cold weather clothing.

Two-level support with Level 1 consisting of a set of beams and Level 2 consisting of a tree-like structure is an efficient support structure for extrusion-based additive manufacturing (EBAM). However, the literature for finding a slim two-level support is rare. The purpose of this paper is to design a lightweight two-level support structure for EBAM.

To efficiently solve the problem, the lightweight design problem is split into two subproblems: finding a slim Level 1 support and a slim Level 2 support. To solve these two subproblems, this paper develops three efficient metaheuristic algorithms, i.e. genetic algorithm (GA), genetic programming (GP) and particle swarm optimization (PSO). They are problem-independent and are powerful in global search. For the first subproblem, considering the path direction is a critical factor influencing the layout of Level 1 support, this paper solves it by splitting the overhang region into a set of subregions, and determining the path direction (vertical or horizontal) in each subregion using GA. For the second subproblem, a hybrid of two metaheuristic algorithms is proposed: the GP manipulates the topologies of the tree support, while the PSO optimizes the position of nodes and the diameter of tree branches. In particular, each chromosome is encoded as a single virtual tree for GP to make it easy to manipulate Crossover and Mutation. Furthermore, a local strategy of geometric search is designed to help the hybrid algorithm reach a better result.

Simulation results show that the proposed method is preferred over the existing method: it saves the materials of the two-level support up to 26.34%, the materials of the Level 1 support up to 6.62% and the materials of the Level 2 support up to 37.93%. The proposed local strategy of geometric search can further improve the hybrid algorithm, saving up to 17.88% of Level 2 support materials.

The proposed approach for sliming Level 1 support requires the overhanging region to be a rectilinear polygon and the path direction in a subregion to be vertical or horizontal. This limitation limits the further material savings of the Level 1 support. In future research, the proposed approach can be extended to handle an arbitrary overhang region, each with several choices of path directions.

The details of how to integrate the proposed algorithm into the open-source program CuraEngine 4.13.0 is presented. This is helpful for the designers and manufacturers to practice on their own 3D printers.

The path planning of the overhang is a critical factor influencing the distribution of supporting points and will thus influence the shape of the support structure. Different from existing approaches that use single path directions, the proposed method optimizes the volume of the support structure by planning hybrid paths of the overhangs.

The characteristics of fine aerosol particles were investigated at an urban site in Beijing during an atmospheric pollution accumulation process. The organics, sulfate and BC were the dominant components in fine particles in the clear air, and the concentrations of organics, sulfate, nitrate and ammonium increased during the haze formation. The mass concentrations of primary species (chloride and BC) in the clear air were similar to those in the haze. The morphology, mixing state and aging status of fine particles in the clear air were different from those in the haze. Accumulation secondary particles were detected with high frequency and accumulation secondary particles with coating were rare in all the samples. The frequency of soot particles with coating in the clear air was lower than that in the haze. The number ratio of accumulation secondary particles to soot containing particles changed from 3:1 in clear air to 2:3 in the haze. These results indicated that the number frequency of accumulation secondary particles decreased while that of the soot containing particles increased with the air pollutants accumulating. The core-shell ratio of coated soot particles ranged between 0.1–0.6 was 62% in the clear air, and 82% in the haze. The mode sizes for the core and the shell of soot particles were 0.35 μm and 0.55 μm in the clear air, and 0.35 μm and 1.0 μm in the haze, respectively. The mean diameters of the core and the shell were 0.3 μm and was 0.6 μm in the clear air, and 0.4 μm and 1.0 μm in the haze, respectively. These results indicated that with the air pollution accumulating, the frequency of accumulation secondary particles decreased while the soot containing particles increased. The aging process of soot particles was stronger in the haze, and resulted in greater hygroscopicity for soot particles in the haze.

To investigate the fluid structure of gravity current in backdraft consisted of the hot gas and the ambient air, to predict the ignition time for backdraft and to study the effect of opening geometries on the ignition time.

Numerical models based on large eddy simulation in fire dynamics simulator are adopted to study the ignition time.

The density (temperature) profiles and velocity fields from the numerical simulation show the typical fluid structure of gravity current, i.e. the slightly raised head, the billows formed behind the head and the lobes and clefts at the leading edge. The increased mixing of gravity current by the ceiling opening geometries comparing to the mixing by the end opening geometries is a result of the three‐dimensional flow. The non‐dimensional velocity presented here is independent of the different normalized density differences, and only depends on the different opening geometries. From this result, it is feasible to predict the ignition time for backdraft in a compartment.

This paper provides a method for predicting the ignition time for backdraft, and offers helps for people, especially firefighters, avoid the hazard from backdraft.

Numerous smog events have occurred in recent years in China. Their hazards in mining and industrial cities are more serious than clear days. The samples were collected in the mining and industrial city of Handan. During the smog episode, PM₁₀ and PM_2.5 concentrations reach up to 980 μg/m³ and 660 μg/m³, respectively. Under SEM (scanning electron microscope) analysis, the particles consist of soot, fly ash and minerals, which could be from coal mines, power plants, steel mills and auto exhausts. Compared with the samples collected on a clear day, the increased PM₁₀ particles are mainly composed of organic matter, especially aromatic compounds. The Pb content in PM₁₀ of the smog day reaches 507.4 ng/m³ and could be caused by vehicle emissions.