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Traditional imperative synchronous programming languages heavily rely on a strict separation between data memory and communication signals. Signals can be shared between computational units but cannot be overwritten within a synchronous reaction cycle. Memory can be destructively updated but cannot be shared between concurrent threads. This incoherence makes traditional imperative synchronous languages cumbersome for the programmer. The recent definition of sequentially constructive synchronous languages offers an improvement. It removes the separation between data memory and communication signals and unifies both through the notion of clock synchronised shared memory . However, it still depends on global causality analyses which precludes procedural abstraction. This complicates reuse and composition of software components. This paper shows how procedural abstraction can be accommodated inside the sequentially constructive model of computation. We present the Sequentially Constructive Procedural Language (SCPL) and its semantic theory of policy-constructive synchronous processes. SCPL supports procedural abstractions using policy interfaces to ensure that procedure calls are memory safe, wait-free and their scheduling is determinate and causal. At the same time, a policy interface constrains the level of freedom for the implementation and subsequent refactoring of a procedure. As a result, policies enable separate compilation and composition of procedures. We present our extensions abstractly as a formal semantics for SCPL and motivate it concretely in the context of the open-source, embedded, real-time language Blech.

Object orientation is a powerful and widely used paradigm for abstraction and structuring in programming. Many languages are designed with this principle or support different degrees of object orientation. In synchronous languages, originally developed to design embedded reactive systems, there are only few object-oriented influences. However, especially in combination with a statechart notation, the modeling process can be improved by facilitating object orientation as we argue here. At the same time the graphical representation can be used to illustrate the object-oriented design of a system. Synchronous statechart dialects, such as the SCCharts language, provide deterministic concurrency for specifying safety-critical systems. Using SCCharts as an example, we illustrate how an object-oriented modeling approach that supports inheritance, can be introduced. We further present how external, i. e. host language, objects can be included in the SCCharts language. Specifically, we discuss how the recently developed concepts of scheduling directives and scheduling policies can be used to ensure the determinism of objects while retaining encapsulation.

A common assumption is that protective devices, such as circuit breakers, in hazardous areas, such as Class I, Division 1 and 2 or Zone 1 and 2, will work at their designed voltage, current, and short- circuit ratings in the same manner as in non-hazardous areas. However, this is not always true. The electrical components of these protective devices can be affected by the type of enclosure used for their installation within a hazardous area. This paper will explore the characteristics and behavior of the short-circuit ratings for electrical equipment installed in a hazardous area. Some factors, such as the type of flammable and combustible material present, play a role in limiting these short-circuit ratings. In addition, material groups create the atmosphere for installed devices and are a deciding factor on short-circuit ratings.

Sparks and hot surfaces are the most common sources of ignition encountered in hazardous locations. However, there is a struggle with how to deal with electronic devices such as medical devices, cell phones, tablet computers, hand-held devices, etc. in a classified area or “Explosive Atmosphere”. It is quite simple to limit the use of cell phones in an explosive atmosphere, but there is much more to consider for the use of other electronic devices. This issue has become a common concern amongst petrochemical companies. While sparks and hot surfaces bring the main risks associated with the operation of equipment in explosive atmosphere, there are also risks derived from static electricity, lightning, stray currents, radio-frequency radiations, electromagnetic waves produced by radio-frequency (RF) transmitters, and optical radiations such as laser radiation. To aid with a potential solution for this problem, this paper will explore the sources, effects, equipment, protection, and standards in Class I, Division 1 (Zone 1) or Division 2 (Zone 2) locations.

A classic challenge in designing reactive systems is how to reconcile concurrency with determinacy. Synchronous languages, such as Esterel, SyncCharts or SCADE, resolve this by providing a semantics that does not depend on run-time scheduling decisions. Esterel's circuit semantics is grounded in physics: An Esterel program is considered valid (constructive) iff it corresponds to a delay-insensitive circuit. The circuit semantics provides on the one hand a mathematically grounded semantics, based on constructive logic, on the other hand it gives a direct path to a data-flow style software implementation. However, Esterel's constructive semantics entails a rather restricted regime for handling sequential accesses to shared data. Thus many programs are rejected as being non-constructive, even though they have a very natural, determinate interpretation. We here present a sequentially constructive circuit semantics (SCC) that lifts this restriction, by distinguishing sequential and concurrent execution contexts. This permits an imperative style familiar to programmers versed in C, for example, without leaving the sound physical foundation of synchronous programming.

Electrical equipment installed within electrically classified areas—Class I, Division 1 (Zone 1), or Division 2 (Zone 2) locations—require techniques to mitigate flame propagation. Class I, Divisions 1 and 2, or explosion-proof (NEMA 7) techniques are the most commonly used for this purpose. Other techniques, such as enclosed break, flame proof, and restricted breathing, are commonly available methods. A previous PCIC paper (Mendler et al. , 2015) explored the electrical arc flash mitigation of the NEMA 7 design. It was found that this design mitigated the electrical arc flash energies, and helped protect personnel from electrical hazard. This paper will explore the percentage reduction in electrical arc flash energies outside the enclosure when an arc occurs inside an enclosure. This will be accomplished using a simpler lighter explosion-protected design. The results will be obtained using an analytical approach, a computational fluid dynamics (CFD) analysis, and with further testing using prototypes that will show enhanced personnel protection.

Most refineries, drilling platforms, and chemical plants are equipped with receptacles used for powering equipment. This can present a shock hazard; therefore, NFPA and OSHA require ground-fault circuit interrupter (GFCI) on all receptacles powering equipment used by personnel and are not part of the building permanent wiring. Due to the lack of GFCI at voltages above 240 V, both NFPA and OSHA require employers to implement the assured equipment grounding conductor program for all temporary wiring installations.

This paper evaluates the relationship between hazardous-rated electrical equipment, which is suitable for installation in Class I, Division 1 (Zone 1), or Division 2 (Zone 2) locations, and an arc-rated switchgear, which is designed to withstand the effects of an internal arcing fault. Using UL 1203 (Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations), IEEE C37.20.7 (IEEE Guide for Testing Metal-Enclosed Switchgear Rated Up to 38 kV for Internal Arcing Faults), and the paper titled “Pressure Developed by Arcs,” this paper will explore the applicability of hazardous-rated equipment in the protection of personnel from an arc-flash hazard.

This paper will explore the maintenance of electrical equipment. Specifically it will look at: 1) Why maintenance is performed on electrical equipment? 2) What, legal or other, drivers are behind performing electrical equipment maintenance? 3) Electrical equipment maintenance is performed on an interval, but what is the purpose of this interval and how is it determined? 4) What is the difference between breakdown, preventive, and predictive electrical equipment maintenance methods and when should each be applied? 5) What do available testing technologies, such as - insulation resistance, power factor, oil analysis, partial discharge, infrared, ultrasonic, functional analysis, etc., tell us about the condition of electrical equipment and when should they be applied to various types of electrical equipment? 6) What does analysis of electrical equipment maintenance data/information reveal about the frequencies, philosophies, and foundation on which maintenance is performed?

This paper reviews how the effectiveness (i.e. the ability to perform an intended function) of electrical systems can be analyzed using the technique of layer of protection analysis (LOPA). LOPA is a process currently in use to determine if instrumented systems are effective in reducing possible risks from the release of hazardous chemicals. This technique can be used to evaluate mandatory protection of electrical systems, non-mandatory protection of electrical systems, alternate system designs, and intervals of maintenance on electrical systems in terms of their potential reliability risks and/or personnel risks. It is shown how LOPA is an additional tool, which can be applied to existing systems or to systems about to be designed, so as to enhance the electrical system effectiveness, reliability, and availability

The scissor between available heart donations and people affected by heart insufficiency opens wider and wider. Good results to support the diseased heart were offered by artificial therapy approaches like a mechanical system that is connected to the left ventricle and works parallel to the heart muscle. The essay presents the designing and optimisation process of such a mechanical blood pump. A innovative design using magnetic and hydraulic forces to avoid mechanical bearings is presented. Built as a brushless axial flux machine it results in a highly integrated drive component with minimized axial length and passive and wearless levitation

Acceptance of International Electrotechnical Commission (IEC) methodology by the National Electric Code (NEC) has given the industry both benefits and concerns. With the American version ("AEx") of the IEC ("Ex") restricted breathing ("nR"), class I, zone 2 rated luminaire, higher wattages are now allowed in areas that were previously inaccessible. In the quest to reduce costs, fewer but higher wattage luminaires is economically a wise choice. Confusion can develop when the "nR" luminaire, which may look exactly like a class I, division 2 luminaire, is installed with class I, division 2 luminaires in a class I, division 2 area. The plant safety personnel are presented with historical maintenance practices, unfamiliar identification, and a lack of education for personnel on the precautions and proper care of this luminaire.

This paper investigates the fuel economy of a hybrid electric vehicle having a 0.1 kWh flywheel energy storage system and a direct injection diesel prime mover engine.