A number of generalized metric spaces have been defined or characterized in terms of g-functions. Symmetric g-functions are discussed by C. Good, D. Jennings and A. M. Mohamad. In this paper, some questions about symmetric g-functions are answered, particularly it is shown that every sym-wg-space is expandable.
In this paper the relations among k-covers, cs*-covers and k-systems are discussed. The following question is partially answered: Does every separable k'-space with a point-countable k-system have a countable k-system?
Authors:C. Lin, Y. Chang, J. Lee, S. Lin, and C. Shu
Preventing accidental explosions of flammable liquid/gas mixtures is very important. As far as flammability characteristics
are concerned, we simulated the effects of inert liquid/gas, which was filled with reactors, vessels, or closed space, employed
in the chemical process industries. The inert liquid/gas (H2O) weakened the oxygen concentration and reduced solvent vapor concentration in a 20-L-Apparatus. This study investigated
the flammability characteristics of acetone/water solutions (100/0, 75/25, 50/50, and 25/75 vol.%) that are controlled at
a temperature of 150°C and pressures of 101/202 kPa, respectively. The flammability parameters included flammability limits
(LEL and UEL), maximum explosion pressure (Pmax), maximum explosion pressure rise ((dP dt−1)max), and vapor deflagration index (Kg). The results of a series of experimental tests showed that UEL, Pmax, and Kg all decreased with steam rising under the experimental conditions. The results can be applied to process safety design/operation
for identifying whether the inert liquid/gas (H2O) content has any substantial effects in reducing the fire and explosion hazard of the solution of interest.
Authors:S. Lin, J. Tseng, Y. Lin, W. Huang, and C. Shu
The polymerization mechanisms of styrene and various derivatives by α-methylstyrene (AMS) and trans-β-methylstyrene (TBMS) were evaluated. Experiments were carried out for dimerization identification and thermal polymerization
estimation by differential scanning calorimetry (DSC), thermal activity monitor (TAM) and Fourier transform infrared absorption
spectrophotometer (FTIR). The results show that, under temperature ranges of 60–190 and 50–170°C, AMS and TBMS performed dimerization
by benzene ring and ethylene double bond, respectively. AMS and TBMS would form unsaturated dimers, saturated dimers and trimers,
etc., during the period of thermal polymerization. Through this study, one can estimate possible intermediates of the polymerization
process for the monomer of interest in the petrochemical industry.
Authors:W. Lin, S. Wu, G. Shiu, S. Shieh, and C. Shu
The highly reactive and unstable exothermal features of methyl ethyl ketone peroxide (MEKPO) have led to a large number of
thermal explosions and runaway reaction accidents in the manufacturing process. To evaluate the self-accelerating decomposition
temperature (SADT) of MEKPO in various storage vessels, we used differential scanning calorimetry (DSC) and vent sizing package
2 (VSP2). The thermokinetic parameters were, in turn, used to calculate the SADT from theoretical equations based on the Semenov
This study aimed at the SADT prediction value of various storage vessels in Taiwan compared with the UN 25 kg package and
UN 0.51 L Dewar vessel. An important index, such as SADT, temperature of no return (TNR) and adiabatic time maximum rate (TMRad), was necessary and useful to ensure safe storage or transportation for self-reactive substances in the process industries.
Authors:S. Cheng, J. Tseng, S. Lin, J. Gupta, and C. Shu
Tert-butyl peroxybenzoate (TBPB) is one of the sensitive and hazardous chemicals which have been popularly employed in petrifaction
industries in the past. This study attempted to elucidate its unsafe characteristics and thermally sensitive structure so
as to help prevent runaway reactions, fires or explosions in the process environment. We employed differential scanning calorimetry
(DSC) to assess the kinetic parameters (such as exothermic onset temperature (T0), heat of reaction (ΔH), frequency factor (A)), and the other safety parameters using four different scanning rates (1, 2, 4 and 10°C min−1) combined with curve-fitting method.
The results indicated that TBPB becomes very dangerous during decomposition reactions; the onset temperature and reaction
heat were about 100°C and 1300 J g−1, respectively. Through this study, TBPB accidents could be reduced to an accepted level with safety parameters under control.
According to the findings in the study and the concept of inherent safety, TBPB runaway reactions could be thoroughly prevented
in the relevant plants.
Authors:J. Chen, S. Wu, S. Lin, H. Hou, and C. Shu
The exothermic decomposition of cumene hydroperoxide (CHP) in cumene liquid was characterized by isothermal microcalorimetry,
involving the thermal activity monitor (TAM). Unlike the exothermic behaviors previously determined from an adiabatic calorimeter,
such as the vent sizing package 2 (VSP2), or differential scanning calorimetry (DSC), thermal curves revealed that CHP undergoes
an autocatalytic decomposition detectable between 75 and 90°C. Previous studies have shown that the CHP in a temperature range
higher than 100°C conformed to an nth order reaction rate model. CHP heat of decomposition and autocatalytic kinetics behavior were measured and compared with
previous reports, and the methodology and the advantages of using the TAM to obtain an autocatalytic model by curve fitting
are reported. With various autocatalytic models, such as the Prout-Tompkins equation and the Avrami-Erofeev rate law, the
best curve fit among models was also investigated and proposed.
Authors:S. Chiu, P. Wang, P. Kao, J. Lin, D. Lin, and C. Chen
Hair samples from junior high school students in metropolitan areas of Taichung, Taiwan were tested for a total of 13 elements,
Al, Ag, Br, Cl, Cr, Fe, K, La, Mn, Na, Sc, Se, and Zn by instrumental neutron activation analysis (INAA) to establish seasonal
variations, gender and environmental exposures. The seasonal variations of hairs in 39 healthy students (18 males and 21 females;
age 13.3 ± 0.4 years; height, 158.0 ± 4.1 cm; weight, 53.4 ± 5.7 kg) were collected at 1.5-month intervals for 1 year starting
from late August, 2008. The concentrations of the above elements varied from 103 to 10−2 μg g−1 at different sampling times. A quantified index of agreement (AT) was introduced to help classify the elements. A smaller
AT indicated highly consistent quantities of specific metals in the hair while a larger AT indicated increased fluctuation,
i.e., less agreement. The different ATs in various hair samples were discussed. The concentrations of these elements are compared
with the data in the literature.