Experimental study on fire characteristics in cable compartment of utility tunnel with natural ventilation.

The fire characteristics under natural ventilation in the cable compartment of the utility tunnel are studied. A series of small-scale fire experimental tests are conducted to obtain the maximum temperature below the ceiling of different ignition vertical heights and cable types. In this paper, the ceiling temperature decay and heat release rate (HRR) are studied in the cable compartment of utility tunnel. Through experimental tests, the fire characteristics of placing the fire source on the near wall side 3.0 m away from the shaft of the utility tunnel cable compartment are studied. The results showed that under the action of natural ventilation, with the decrease of fuel quantity, the mass loss of cable decreases, and the maximum temperature below the ceiling of the cable compartment in the utility tunnel decreases. ZRYJV cables burn more sufficient combustion than RVVR cables. A new empirical association for total HRR is proposed. Those experimental test results are used as validation data for the newly proposed empirical correlation of total HRR. This paper hopes to provide some basic fire safety references for the utility tunnel planning of the urban underground cable compartment.

Study on characteristics of fire plume in building facade window under lateral blow.

The overflow of the flame plume from the window is the main cause of the vertical spread of the fire on the facade of the building. This paper considers the geometry of the window by taking measures to prevent the flame from propagating along the vertical wall. In this paper, a residential building is taken as an example to evaluate the flame plume characteristics through experimental tests and numerical simulations. The objective of the present study is to study the flame plume characteristics under the air blow on the outer window side of the building. The theoretical equations of the flame tilt angle, non-dimensional temperature and non-dimensional velocity are derived. A series of experimental tests were carried out in a reduced-scale building model corresponding to the changes of lateral blow ventilation velocity. Reduced scale numerical simulations were conducted to verify the experiments. Results showed that the flame tilt angle increases with ventilation velocity increases. Meanwhile, the experimental results were compared with the reduced-scale tests and numerical simulations. These showed a good agreement between experimental results and numerical simulations. All these findings provide theoretical basis for building fire prevention outside window.

[Bibliometrics and visualization analysis of land use regression models in ambient air pollution research].

Objective: To quantitatively analyze the current status and development trends regarding the land use regression (LUR) models on ambient air pollution studies. Methods: Relevant literature from the PubMed database before June 30, 2017 was analyzed, using the Bibliographic Items Co-occurrence Matrix Builder (BICOMB 2.0). Keywords co-occurrence networks, cluster mapping and timeline mapping were generated, using the CiteSpace 5.1.R5 software. Relevant literature identified in three Chinese databases was also reviewed. Results: Four hundred sixty four relevant papers were retrieved from the PubMed database. The number of papers published showed an annual increase, in line with the growing trend of the index. Most papers were published in the journal of Environmental Health Perspectives. Results from the Co-word cluster analysis identified five clusters: cluster#0 consisted of birth cohort studies related to the health effects of prenatal exposure to air pollution; cluster#1 referred to land use regression modeling and exposure assessment; cluster#2 was related to the epidemiology on traffic exposure; cluster#3 dealt with the exposure to ultrafine particles and related health effects; cluster#4 described the exposure to black carbon and related health effects. Data from Timeline mapping indicated that cluster#0 and#1 were the main research areas while cluster#3 and#4 were the up-coming hot areas of research. Ninety four relevant papers were retrieved from the Chinese databases with most of them related to studies on modeling. Conclusion: In order to better assess the health-related risks of ambient air pollution, and to best inform preventative public health intervention policies, application of LUR models to environmental epidemiology studies in China should be encouraged.

[Applying temporally-adjusted land use regression models to estimate ambient air pollution exposure during pregnancy].

The impact of maternal air pollution exposure on offspring health has received much attention. Precise and feasible exposure estimation is particularly important for clarifying exposure-response relationships and reducing heterogeneity among studies. Temporally-adjusted land use regression (LUR) models are exposure assessment methods developed in recent years that have the advantage of having high spatial-temporal resolution. Studies on the health effects of outdoor air pollution exposure during pregnancy have been increasingly carried out using this model. In China, research applying LUR models was done mostly at the model construction stage, and findings from related epidemiological studies were rarely reported. In this paper, the sources of heterogeneity and research progress of meta-analysis research on the associations between air pollution and adverse pregnancy outcomes were analyzed. The methods of the characteristics of temporally-adjusted LUR models were introduced. The current epidemiological studies on adverse pregnancy outcomes that applied this model were systematically summarized. Recommendations for the development and application of LUR models in China are presented. This will encourage the implementation of more valid exposure predictions during pregnancy in large-scale epidemiological studies on the health effects of air pollution in China.

[Contribution of different sources of exposure to particulate matter in an elderly community in Tianjin].

OBJECTIVE: To determine the pollution sources that influence the level of exposure to particulate matter 2.5 (PM2.5) in the elderly, and calculate the quantitative contributions of difference sources. METHODS: Personal exposure PM samples were collected in the summer and winter of 2011 from 101 elderly men in a Tianjin community. Chemical species (elements, water-soluble ions and carbonaceous species) were analyzed in PM samples to determine PM2.5 concentrations and chemical compositions. The Positive Matrix Factorization (PMF) model, which is recommended by the US Environmental Protection Agency, was employed to quantitatively analyze the contribution of each potential sources to personal levels of PM2.5 exposure. RESULTS: In both summer and winter, the model identified the same six sources of personal exposure to PM2.5 in the elderly: fugitive dust (marker species: Si, Al, Ca, Mg, Fe etc.), coal combustion emissions (marker species: organic carbon (OC) and SO4(2-)), vehicle exhausts (marker species: inorganic carbon and NO3-), secondary sulfates and nitrates (marker species: NO3-, SO42- and NH4(+)), industrial emissions (marker species: Mn, Ni, Cu, Zn, Pb etc.), and indoor sources (marker species: OC, K, Si, Al etc.). Among these six potential sources, vehicle exhausts (summer: 33.6%, winter: 24.2%), secondary sulfates and nitrates (summer: 27.4%, winter: 29.1%), as well as coal combustion emissions (summer: 19.9%, winter: 24.1%) were the greatest contributors. CONCLUSIONS: Coal combustion and vehicle exhaust emissions were the major sources of personal exposure to PM2.5 in the elderly, suggesting that these two sources were the key contributors to the precursor gases of secondary sulfate and nitrate.

Determination of trace amounts of vanadium with a new reagent [1-(3-methoxysalicylidene-amino)-8-hydroxy-3,6-naphthalene disulfonic acid, disodium salt] by fluorescence quenching method.

A fluorescence quenching method is described for the determination of trace amounts of vanadium(V) based on the formation of a complex in acidic medium with a new reagent [1(3-methoxysalicylideneamino)-8-hydroxy-3,6-naphthalene disulfonic acid, disodium salt]. The fluorescence emission is measured at 415 nm (wavelength of excitation 360 nm), and the experimental variables and interferences in this determination have been studied. The detection limit is 12.5 ng/ml and linear range is between 50 and 600 ng/ml. The method has been applied to determine trace vanadium(V) in steel and cast iron.