Managing your process hazards as a means of conforming to ohsa requirements

There is considerable evidence that improper changes have directly caused or through the “domino sequence” led to many of the major accidents that have occurred in the chemical process industry and related industries that use hazardous chemicals and technology. Central Government has recognised the importance of careful management of change(MOC) for ensuring the safety of chemical operations and the quality of manufactured goods by the proposed adding of the Major Hazardous Installation Regulation to the OHSA (Act 85 of 1993).

The concept and the need to properly manage change are not new; many companies have adopted MOC procedures. It is common practice nowadays to perform detailed risk assessments on any new or intended project to ensure safety and reliability of the project. Yet, incidents and near misses attributable to inadequate management of changes on existing systems and processes continue to occur. To improve the performance of MOC systems throughout industry, managers need advice on how to better institutionalise MOC systems within their companies and plants.

The purpose of this paper is to define the important features of MOC systems and to assist in the implementation and management of process hazards. MOC systems help ensure that changes to design and operation of company facilities will not adversely affect employees, the public, or the environment. This document outlines a process that can be used for designing, developing, installing, operating, and maintaining MOC systems at individual company sites.

This paper is intended for an audience ranging from plant and corporate managers of process safety to workers who have differing levels of knowledge about the principles of safely managing change. It is primarily designed to equip people responsible for MOC systems with new ideas for implementing and improving MOC systems. It was indeed a privilege to have met the personnel of JBF Associates, Inc. and Process Safety Institute in Knoxville, Tennessee, USA, without whose lectures and study material (including the book “Managing process changes”) this paper would never have seen the light. They have succeeded in putting me firmly on the “process safety road”.     

Evaluation of Serum Volume Losses During Long-Term Storage

Aliquots of serum collected in a large case-control study of cervical cancer were stored at −70°C for up to 4 years during implementation of the study. When 500 μL serum aliquots were thawed in preparation for carotenoid and vitamin A assays, volumes were noticeably variable and fell below 500 μL in the majority of the samples. We were concerned about evaporation/sublimation during storage of the samples because loss of water would concentrate the analytes of interest. We evaluated the use of density and sodium ion concentration measurements to confirm its occurrence. We found that serum density was an unreliable indicator of extent of volume loss since the anticipated increases in density due to evaporation were of the same magnitude as inter-individual variation in serum density. In contrast, Na⁺ concentration is tightly regulated and would rise if water had been lost from the samples. In a representative sample of serum aliquots from the case-control study, 24 of 25 vials contained less than 500 μL of serum. The mean sodium ion concentration (138.1 ± 3.6 mmol/L) was within the normal range for human serum of 136–145 mmol/L, and no correlation was observed between serum volume and Na⁺ concentration. These results strongly suggest that the observed low volumes were not due to evaporative losses. Instead, the variably low volumes of serum aliquots were probably due to pipetting errors in the initial aliquotting resulting from the use of air-displacement pipettes.     

Two CEGAR-based approaches for the safety verification of PLC-controlled plants

In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider a specification of the control program of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid models can be transformed to hybrid automata, for which advanced techniques for reachability analysis exist. However, the hybrid automata models are often too large to be analyzed. We propose two counterexample-guided abstraction refinement (CEGAR) approaches to keep the size of the hybrid models moderate.     

Transforming Perceived Vocal Effort and Breathiness Using Adaptive Pre-Emphasis Linear Prediction

This paper presents a technique to transform high-effort voices into breathy voices using adaptive pre-emphasis linear prediction (APLP). The primary benefit of this technique is that it estimates a spectral emphasis filter that can be used to manipulate the perceived vocal effort. The other benefit of APLP is that it estimates a formant filter that is more consistent across varying voice qualities. This paper describes how constant pre-emphasis linear prediction (LP) estimates a voice source with a constant spectral envelope even though the spectral envelope of the true voice source varies over time. A listening experiment demonstrates how differences in vocal effort and breathiness are audible in the formant filter estimated by constant pre-emphasis LP. APLP is presented as a technique to estimate a spectral emphasis filter that captures the combined influence of the glottal source and the vocal tract upon the spectral envelope of the voice. A final listening experiment demonstrates how APLP can be used to effectively transform high-effort voices into breathy voices. The techniques presented here are relevant to researchers in voice conversion, voice quality, singing, and emotion.     

Requirements for a virtual environment to support the social participation education of low-literates

People of low literacy experience difficulties while participating in society. Learning support software could help alleviate these difficulties. However, there is currently no overview of theoretically and empirically sound requirements for this kind of support. This paper uses the situated cognitive engineering method to create a requirements baseline for a virtual environment to support the societal participation education of low-literates (VESSEL), based on an analysis of the domain, human factors, and current applications. Four major outcomes are presented. First, a comprehensive overview is collected of the operational demands and human factors knowledge relevant to societal participation learning for low-literate citizens. Second, this overview is translated into a list of eight functional requirements: focused on low-literate learners, set in the context of societal participation, and supported by claims of cognitive, affective, and social benefits to learning. Third, a sample of Dutch societal participation learning support programs is assessed using these requirements, to highlight both current technology best practices and discrepancies between theory and practice. Fourth, virtual learning environment technology is suggested as an ‘enabling’ technology; an overview is shown of how virtual environments, actors, and objects can beneficially enable meeting the requirements baseline. Finally, directions for future study are discussed.

     

Photobleaching with phloxine B sensitizer to reduce food matrix interference for detection of Escherichia coli serotype O157:H7 in fresh spinach by flow cytometry

A flow cytometric method (RAPID-B™) with detection sensitivity of one viable cell of Escherichia coli serotype O157:H7 in fresh spinach (Spinacia oleracea) was developed and evaluated. The major impediment to achieving this performance was mistaking autofluorescing spinach particles for tagged target cells. Following a 5 h non-selective enrichment, artificially inoculated samples were photobleached, using phloxine B as a photosensitizer. Samples were centrifuged at high speed to concentrate target cells, then gradient centrifuged to separate them from matrix debris. In external laboratory experiments, RAPID-B and the reference method both correctly detected E. coli O157:H7 at inoculations of ca. 15 cells. In a follow-up study, after 4 cell inoculations of positives and 6 h enrichment, RAPID-B correctly identified 92% of 25 samples. The RAPID-B method limit of detection (LOD) was one cell in 25 g. It proved superior to the reference method (which incorporated real time-PCR, selective enrichment, and culture plating elements) in accuracy and speed.     

Effect of molecular weight distribution on polymer diffusion during film formation of two-component high-/low-molecular weight latex particles

We describe fluorescence resonance energy transfer (FRET) studies of film formation by a new type of two-component latex particles. These particles consist of a miscible blend of two components that have a similar composition but very different molecular weights. In our approach, we used sequential seeded emulsion polymerization to generate (in situ) a fraction of oligomer in poly(butyl acrylate-co-methyl methacrylate) P(BA-MMA) seed particles that contained a relatively high molecular weight (high-M) dye-labeled polymer. In this way we could systematically change the molecular weight distribution of polymer inside the particles. We varied the amount and the molecular weight of the oligomers. For latex films cast from these two-component particles, we studied the diffusion rate of the high molecular weight polymer by FRET. These measurements revealed that oligomers promoted diffusion rate during latex film formation (oligoplasticization). We analyzed our diffusion data in terms of the Fujita–Doolittle free-volume model and showed that higher molecular weight oligomers are less efficient as plasticizers. In separate experiments, oligomers with similar molecular weights as those in the two-component particles were introduced via latex blending. We compared oligoplasticization in latex blends films with that in the two-component particles films. Finally, we investigated the rheological behavior of the two-component polymers with compositions adjusted to have a common T_g (2 °C). The higher the molecular weight of the oligomer, the more that had to be added to achieve T_g = 2 °C. All of the oligomers were much shorter than the entanglement length and act as diluents of the entanglements in the high-M polymer. We found that incorporating larger amounts of oligomers with a higher molecular weight resulted in a more pronounced drop in polymer viscosity, associated with the decrease in the entanglement density.     

The elasticity of capital-labour substitution in Singapore construction

A central issue in improving construction productivity is the flexibility in which capital and labour may be substituted. Empirical estimation using Singapore data suggests that the hypothesis of a unitary elasticity of substitution cannot be rejected, thereby providing justification for policy measures to alter the relative prices of factor inputs to encourage mechanisation in construction. The finding is consistent with an earlier study on the American construction industry as well as numerous production function studies conducted for other industries.