On dioxin formation in iron ore sintering

Iron ore sintering is an important source of "dioxins", polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This paper reports on attempts to identify materials, conditions, and mechanisms responsible for PCDD/F formation (i) by investigating salient properties of ores (viz., with respect to oxidation, condensation, and chlorination of model organics) and (ii) by mimicking the industrial process on a microscale with real-life materials. Principles of Design of Experiments (DOE) are employed. The reactivities of iron ores differ greatly. Limonite/goethite "soft" ore is a very active oxidation catalyst (e.g., for benzene and phenol), a property that may be useful in cleaning up crude sintering process offgases, whereas hematite/magnetite "hard" ore is not. The latter, however strongly promotes condensation of phenol to dibenzofuran. A newly built lab-microscale sintering facility could satisfactorily imitate the large-scale process, in part or as a whole. Results obtained with realistic feed mixtures point at dioxin formation in the sinter bed at levels significant enough to explain a major part of the outputs observed in the real-life process. With approximately 8 ppm (wt) of chloride added as NaCl, the PCDD/F output doubled, but with the same proportion of chlorine administered as C2Cl4, the dioxin output was over 2 orders of magnitude larger. The use of process reverts, etc. containing chlorinated organics should therefore be avoided. PCDD/F congener patterns are also reported and compared with those observed in practice.     

Gene regulation in response to protein disulphide isomerase deficiency

We have examined the activities of promoters of a number of yeast genes encoding resident endoplasmic reticulum proteins, and found increased expression in a strain with severe protein disulphide isomerase deficiency. Serial deletion in the promoter of the MPD1 gene, which encodes a PDI1-homologue, revealed a cis-acting element responding to deficiency of protein disulphide isomerase activity (designated CERP). The presence of the sequence element is necessary and sufficient for the upregulation in response to disulphide isomerase deficiency, as measured by a minimal promoter containing the CERP element. The sequence (GACACG) does not resemble the unfolded protein response element. It is present in the upstream regions of the MPD1, MPD2, KAR2, PDI1 and ERO1 genes.     

Tape casting system for ULTCCs to fabricate multilayer and multimaterial 3D electronic packages with embedded electrodes

A 3D multilayer structure built by two ultra‐low temperature co‐fired ceramic (ULTCC) compositions with silver embedded electrodes are co‐fired at a temperature of 450°C. The 3D multilayer module is prepared by laminating the ULTCC green tapes with a new binder system, which organics can be completely burned out at temperature of 250°C before the sintering of the ULTCC 3D modulus. High‐density microstructures are achieved for the sintered module. In this study, the ULTCC feasible binder system is introduced. Also, ULTCC multilayers and multimaterial structures with surface and embedded silver electrodes are fabricated. This research opens up a new horizon for fabrication of electroceramic devices with embedded electrodes in multimaterial devices.     

Effect of high rate deformation induced precipitation hardening on the failure of aluminium rivets

Aluminium alloy (7050-T73) rivets were fabricated by an electromagnetic riveting process. Each rivet was formed in less than 500sec. Microcracks and severely deformed regions were observed in the rivet head. Microprobe analysis, optical and scanning electron microscopic examination on the rivets did not yield conclusive evidence that the microcracks were caused by impurities such as iron and silicon. The data obtained in this study support the view that heat generated by material flow at high speed in the rivet head induced precipitation hardening. The precipitation hardening significantly increased the material hardness in the severely deformed shear zone. It Is believed that the increment of hardness in the shear zone of the rivets fabricated from the slugs which were previously age hardened resulted in a further decrease in ductility. Hence the initiation of voids which subsequently coalesced to form microcracks in the shear zone.     

Crystal defects and coherent intergrowth of α- and β-crystals in Y-Ce doped sialon materials

Sialon material doped with a mixture of yttrium and cerium in a molar ratio of 1 to 3, up to a total amount of 6 wt% has been investigated with high resolution transmission electron microscopy (HREM). The-sialon crystals were shown to contain defects of types not previously reported. These include stacking faults, shear and coherent intergrowth of- and-sialon crystals. For some of the defects structural models are proposed and verified by image simulations.     

The successor representation and temporal context

The successor representation was introduced into reinforcement learning by Dayan ( 1993 ) as a means of facilitating generalization between states with similar successors. Although reinforcement learning in general has been used extensively as a model of psychological and neural processes, the psychological validity of the successor representation has yet to be explored. An interesting possibility is that the successor representation can be used not only for reinforcement learning but for episodic learning as well. Our main contribution is to show that a variant of the temporal context model (TCM; Howard & Kahana, 2002 ), an influential model of episodic memory, can be understood as directly estimating the successor representation using the temporal difference learning algorithm (Sutton & Barto, 1998 ). This insight leads to a generalization of TCM and new experimental predictions. In addition to casting a new normative light on TCM, this equivalence suggests a previously unexplored point of contact between different learning systems.     

Fuzzy stochastic data envelopment analysis with application to base realignment and closure (BRAC)

Data envelopment analysis (DEA) is a non-parametric method for evaluating the relative efficiency of decision-making units (DMUs) on the basis of multiple inputs and outputs. Conventional DEA models assume that inputs and outputs are measured by exact values on a ratio scale. However, the observed values of the input and output data in real-world problems are often vague or random. Indeed, decision makers (DMs) may encounter a hybrid uncertain environment where fuzziness and randomness coexist in a problem. Several researchers have proposed various fuzzy methods for dealing with the ambiguous and random data in DEA. In this paper, we propose three fuzzy DEA models with respect to probability-possibility, probability-necessity and probability-credibility constraints. In addition to addressing the possibility, necessity and credibility constraints in the DEA model we also consider the probability constraints. A case study for the base realignment and closure (BRAC) decision process at the U.S. Department of Defense (DoD) is presented to illustrate the features and the applicability of the proposed models.     

Crossover can be constructive when computing unique input�Coutput sequences

Unique input–output (UIO) sequences have important applications in conformance testing of finite state machines (FSMs). Previous experimental and theoretical research has shown that evolutionary algorithms (EAs) can compute UIOs efficiently on many FSM instance classes, but fail on others. However, it has been unclear how and to what degree EA parameter settings influence the runtime on the UIO problem. This paper investigates the choice of acceptance criterion in the (1 + 1) EA and the use of crossover in the (m+1)(\mu+1) Steady State Genetic Algorithm. It is rigorously proved that changing these parameters can reduce the runtime from exponential to polynomial for some instance classes of the UIO problem.     

Ensuring mooring line integrity by dynamic positioning: Controller design and experimental tests

This paper addresses the dynamic positioning of surface vessels moored to the seabed via a turret based spread mooring system, an operation referred to as the position mooring. While the mooring system keeps the surface vessel in place most of the time, thruster assistance is needed in severe weather conditions to avoid mooring line failure. Traditionally, this is done by keeping the vessel within a predefined geographical region. We present a conceptually new controller for position mooring operations. By using a structural reliability measure for the mooring lines, the new controller protects the mooring system whenever needed as a result of severe weather conditions and high environmental loads. This is done by maintaining the probability of mooring line failure below a preset value. In particular, the excessive use of thrusters caused by conservatively defined safety regions in conventional PM systems is avoided, giving a fuel optimal operation. The feasibility of our controller is successfully verified in laboratory experiments.     

A comparison of managers' and safety delegates' perceptions of work environment priorities in the manufacturing industry

This study investigated the attention and priority accorded to factors of work environment within manufacturing companies, as perceived by managers and safety delegates at small‐ and medium‐sized enterprises. Representatives from 142 Swedish manufacturing companies answered a 43‐item questionnaire covering seven areas of the work environment and a priority‐ranking question of company interests. Respondents (n = 249) rated the present situation and the situation one year earlier, using a visual analogue scale. The findings showed that both managers and safety delegates ranked profitability as the main company interest. Respondents rated the priorities of the work environment currently as higher than one year earlier (p = <0.05). Managers rated the priorities of the work environment higher than did the safety delegates (p = <0.05). We conclude that the two professional roles, manager and safety delegate, differ in their perceptions regarding to what extent different work environment factors are being attended to. © 2011 Wiley Periodicals, Inc.