Dynamic alarm prediction for critical alarms using a probabilistic model

Alarm systems play important roles for the safe and efficient operation of modern industrial plants. Critical alarms are configured with a higher priority and are safety related among many other alarms. If critical alarms can be predicted in advance, the operator will have more time to prevent them from happening. In this paper,we present a dynamic alarm prediction algorithm, which is a probabilistic model that utilizes alarm data from distributed control system, to calculate the occurrence probability of critical alarms. It accounts for the local interdependences among the alarms using the n-gram model, which occur because of the nonlinear relationships between variables. Finally, the dynamic alarm prediction algorithm is applied to an industrial case study.

Controlling Thermal Conduction by Graded Materials

Manipulating thermal conductivities are fundamentally important for controlling the conduction of heat at will. Thermal cloaks and concentrators, which have been extensively studied recently, are actually graded materials designed according to coordinate transformation approaches, and their effective thermal conductivity is equal to that of the host medium outside the cloak or concentrator. Here we attempt to investigate a more general problem: what is the effective thermal conductivity of graded materials? In particular, we perform a first-principles approach to the analytic exact results of effective thermal conductivities of materials possessing either power-law or linear gradation profiles. On the other hand, by solving Laplace's equation, we derive a differential equation for calculating the effective thermal conductivity of a material whose thermal conductivity varies along the radius with arbitrary gradation profiles.The two methods agree with each other for both external and internal heat sources, as confirmed by simulation and experiment. This work provides different methods for designing new thermal metamaterials(including thermal cloaks and concentrators), in order to control or manipulate the transfer of heat.

Concentrations and distributions of Dechlorane Plus in environmental samples around a Dechlorane Plus manufacturing plant in East China

A comprehensive investigation into the occur- rence of Dechlorane Plus （DP） in environmental samples around a DP manufacturing plant in East China was per- formed. The total syn-DP and anti-DP concentrations found in the soil, sediment, active air, and passive air samples were 0.50-2,315 pg/g dry weight （dw）, 0.32-20.5 ng/g dw, 5.52-3,332 pg/m^3, and 1.00-4,560 pg/m^3, respectively. There were consistent trends in the spatial distributions of DP in the soil and air samples, with the DP concentrations de- creasing dramatically as the distance from the plant in- creased. The mean anti-DP isomer fractional abundances （fanti） in the soil, sediment, active air, and passive air samples were 0.67, 0.68, 0.70, and 0.64, respectively. These fanti values were consistent with the fanti value for the technical DP produced in the DP manufacturing plant （0.68）, meaning that the DP had been released during the local DP production activities.