The situational reflection of reality in activity theory and the concept of situation awareness in cognitive psychology

This article presents new data from the implementation of Activity Theory and integrates it with some concepts of cognitive psychology. The main focus is on orienting activity, which is directed to comprehending and interpreting reality as well as predicting future events' significance for the performance of present events. The concept of orienting activity is directly related to what is known as Situation Awareness (SA) in the US. However, the concept of orienting activity is broader than that of SA. Orientation and comprehension of a situation includes not only conscious and verbally logical components, but also unconscious components. The imaginative elements of the activity and the non-verbalized meaning of the situation are important in the unconscious reflection of reality. This paper describes SA as one of the important function mechanisms involved in the dynamic reflection of the situation. Other important elements of this dynamic reflection are its emotional and motivational components.     

Experimental and numerical study of transient natural convection due to mass transfer in inclined enclosures

Both experiments and numerical work are performed to study transient natural convection flow and transport process due to mass transfer in the enclosures inclined at different angles. In the experiments, the enclosure is filled with aqueous solution containing CuSO₄ + H₂SO₄ where the flow structure can be visualized by both particle tracer and shadowgraph. Two opposed side walls of the enclosure are maintained at different concentrations which are made by passing current through the electrodes at the limiting condition. All the other side walls are made insulated and impermeable to the species transfer. Both the concentration distribution and its fluctuations are measured with non-intrusive optical method. During the experiments, the Rayleigh number ranges from 1.126 × 10⁸ to 1.157 × 10¹¹, the angles of inclination from 30 to 90 degree and the aspects ratio of the enclosure from 0.6 to 1. Comparison between the data and prediction is made and discussed at various conditions.     

Tribological properties of the AZ91D magnesium alloy hardened with silicon carbide and by severe plastic deformation

Results of investigation of the tribological contact characteristics of R18 tool steel in interface with AZ91D magnesium alloy hardened with SiC disperse powder filler and by severe plastic deformation (SPD)—specifically, equal-channel angular pressing (ECAP)—are presented. It is established that introduction of the SiC powder filler into the magnesium alloy increases the friction coefficient and reduces the wear rate. The size and volume of the powder filler particles, the normal load, and the relative sliding velocity influence these tribological characteristics. SPD of the original material leads to reduction of the molecular component of the friction coefficient.     

Combined design and load shifting for distributed energy system

Renewable distributed energy generation (DEG) system plays an important role in future power developments and is one of the options to reduce energy consumption. It is envisaged that energy efficiency of DEG systems can be improved via load shifting (LS). This study proposed a heuristic-based numerical approach to perform LS analysis on renewable stand-alone DEG systems. The technique is an extension from a method known as the Electric System Cascade Analysis (ESCA). The new technique, which focuses on efficient electricity utilisation is able to determine the optimal: (i) load profiles, (ii) capacity of power generator, (iii) capacity and power of energy storage (ES) and (iv) charging/discharging schedule of ES. The stage-wise technique allows user to compare and determine the optimal design in a flexible way while having a better understanding of the selection of options. The application of ESCA-LS on a case study revealed that after incorporation of direct LS (load manipulation) in addition to LS by ES (supply manipulation), the power generators and ES capacity can be further reduced. While reduction of 3.1 % for solar-PV installation area and 3.9 % for biomass power generator is recorded, ES power-related capacity and energy-related capacity managed a higher reduction of up to 19.0 and 13.2 % for the main case study     

Petri‐net based integer programs for synthesizing optimal material‐transfer procedures in pipeline networks

Abstract

Transferring materials through the pipeline network is a basic operation in almost every batch chemical plant. Traditionally, the tasks for conjecturing the needed operation steps are carried out manually on an ad hoc basis. This approach is often time‐consuming for industrial processes and, furthermore, the resulting recipe may be error‐prone. The aim of this paper is thus to develop a systematic strategy to generate the optimal operating procedures with Petri‐net based integer programs. Specifically, the shortest material‐transfer routes are selected on the basis of Petri‐net representation of the path structure in pipeline network. The equipment models are then incorporated into this path model to create a complete system model. An integer program can therefore be constructed accordingly to identify the detailed operation steps. Finally, a realistic example is presented at the end of this paper to demonstrate the effectiveness and correctness of the proposed approach.     

SHORT-CRESTED WAVE-INDUCED SEABED RESPONSE VARIABLE PERMEABILITY

ABSTRACT

The soil permeability of marine sediments varies with burial soil depth because of consolidation under overburden pressure. However, most previous investigations available for water wave-seabed interaction problem have simply assumed seabed with uniform permeability. This paper proposes an analytical solution to investigate the short-crested wave-induced soil response in a porous seabed with variable permeability. The pore pressure and effective stresses generated by a three-dimensional short-crested wave system are obtained from a set of equations incorporating a variable permeability. The numerical results indicate that the effect of variable permeability on the wave- induced soil response is significant.     

Phosphorus‐containing epoxy resin for an electronic application

A phosphorus‐containing epoxy resin, 6‐H‐dibenz[c,e][1,2] oxaphosphorin‐6‐[2,5‐bis(oxiranylmethoxy)phenyl]‐6‐oxide (DOPO epoxy resin), was synthesized and cured with phenolic novolac (Ph Nov), 4,4′‐diaminodiphenylsulfone (DDS), or dicyandiamide (DICY). The reactivity of these three curing agents toward DOPO epoxy resin was found in the order of DICY > DDS > Ph Nov. Thermal stability and the weight loss behavior of the cured polymers were studied by TGA. The phosphorus‐containing epoxy resin showed lower weight loss temperature and higher char yield than that of bisphenol‐A based epoxy resin. The high char yields and limiting oxygen index (LOI) values as well as excellent UL‐94 vertical burn test results of DOPO epoxy resin indicated the flame‐retardant effectiveness of phosphorus‐containing epoxy resins. The DOPO epoxy resin was investigated as a reactive flame‐retardant additive in an electronic encapsulation application. Owing to the rigid structure of DOPO and the pendant P group, the resulting phosphorus‐containing encapsulant exhibited better flame retardancy, higher glass transition temperature, and thermal stability than the regular encapsulant containing a brominated epoxy resin. High LOI value and UL‐94 V‐0 rating could be achieved with a phosphorus content of as low as 1.03% (comparable to bromine content of 7.24%) in the cured epoxy, and no fume and toxic gas emission were observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 353–361, 1999     

A Heuristic Search Approach Using Approximate Solutions to Petri Net State Equations for Scheduling Flexible Manufacturing Systems

This paper proposes a new heuristic search approach based on an analytic theory of the Petri net state equations for scheduling flexible manufacturing systems (FMSs) with the goal of minimizing makespan. The proposed method models an FMS using a timed Petri net and exploits approximate solutions of the net's state equation to predict the total cost (makespan) from the initial state through the current state to the goal. That is, the heuristic function considers global information provided by the state equation. This makes the method possible to obtain solutions better than those obtained using prior works (Lee and DiCesare, 1994a, 1994b) that consider only the current status or limited global information. In addition, to reduce memory requirement and thus to increase the efficiency of handling larger systems, the proposed scheduling algorithm contains a procedure to reduce the searched state space.     

Phosphorus containing epoxy for flame retardant II: Curing reaction of bis-(3-glycidyloxy) phenylphosphine oxide

The curing reaction of a phosphorus containing epoxide, bis-(3-glycidyloxy) phenylphosphine oxide (BGPPO), was studied by differential scanning calorimeter (DSC) using dynamic and isothermal methods. Kinetic parameters and activation energy of the BGPPO cured with diamine or dianhydride curing agents were determined. The dynamic activation energies were significantly larger than the isothermal ones. Via isothermal analysis technique, the activation energies of BGPPO cured with 4,4′-diaminodiphenylmethane, dicyanodiamide, methyl tetrahydrogen phthalic anhydride, and phthalic anhydride were found to be 69.5, 83.5, 93.6, and 90.6 kJ/mol, respectively. These values were comparable with those of other commercial epoxy curing system. © 1996 John Wiley & Sons, Inc.