Risk management for safety operation utilizing virtual reality simulation supported by intelligent HAZOP analysis

Ensuring safe operability and minimizing risk is the key component to prevent negative impact in all industries dealing with toxic, reactive, flammable and explosive materials. HAZOP (Hazard and Operability), a preliminary and systematic approach for identifying hazards has been unquestionably successful in reducing incident of hazards by mitigating the consequence of major accident in the industrial process facilities. However, laborious work, time and cost are the shortcoming in performing and maintaining HAZOP analysis. Many research works on HAZOP automation are available, yet the traditional approach is still widely used by plant operators. The traditional method only covers parts and aspects of a specific plant type rather than generalizing to fit many plant types. In HAZOP analysis of chemical process industries (CPI), process analysis can be divided into two groups - defined or routine process, which roughly occupies 60-80% and predefined or non routine process, which occupies 20-60% of HAZOP analysis. Thus leading towards the significance of having safety information as update and accessible as possible. In recent years, computer hardware capable of developing and running virtual reality model has become more affordable for middle and small scale CPI. Consequently, virtual reality has been proposed as a technological breakthrough that holds the power to facilitate analysis. The ability to visualize complex and dynamic systems involving personnel, equipment and layouts during any real operation is a potential advantage of such an approach. With virtual reality supporting HAZOP, analysis which often solely relied on expert imaginative thinking in simulating hazard conditions, will aid understanding, memory retention and create a more interactive analysis experience. In focusing assessment for safety operator and safety decision maker, we present a web-based HAZOP analysis management system (HMS) to help HAZOP team and related individuals to perform revision, tracking and even complete HAZOP analysis without management bureaucracy. Besides, depending solely on expert imaginative thinking of scenario using P&ID, this work will develop a dynamic visual model which brings to the user a different view of consequent and subsequent to an accident and will further enable three dimensional analyses of effects. This approach will prevent ‘miss looks’ due to ‘paper-based’ view. We also present Virtual HAZOP Training system, a risk-managing virtual training concept supported by intelligent HAZOP proposed to eliminate analysis redundancies and bring static ‘paper-based’ analysis to more dynamic and interactive virtual analysis simulation. However, the efficiency of VR simulator depends on the scenario accuracy to the real world that can be simulated. We introduce the system’s artificial intelligent engine responsible for retrieving the most accurate and highest possibility ‘to-happen’ scenario case. A fuzzy – CBR method enables the engine to classify and use real past scenarios combined with suitable parameters in creating a defined scenario. This method resolves issues in balancing between computational complexity and knowledge elicitation Reactor section in a vacuum gas oil hydrodesulphurization (VGO HDS) process is used as the case study to illustrate the performance of the proposed system. The wide usages of HDS unit in the petroleum refining industry play important roles in chemical plant incidents happening worldwide. HAZOP analysis management system in average manages to reduce more than half the time required in performing HAZOP analysis compares to traditional method. With the proposed system, operator is able to optimally use safety information in HMS to prevent common and repetitive mistakes. Virtual process and accident simulator available in virtual HAZOP training system help to improve safety operator estimate overall impact towards equipment, operator and environment during process 20-35% better. This system is expected to be the main foundation for Virtual Reality simulator research in analyzing accident caused by human factor. Asides providing better and healthier working environment, negative profitability impact which influence not only the company that runs it but also the world economy due to byproduct shortage, can be avoided

Octave-spanning broadband absorption of terahertz light using metasurface fractal-cross absorbers

Synthetic fractals inherently carry spatially encoded frequency information that renders them as an ideal candidate for broadband optical structures. Nowhere is this more true than in the terahertz (THz) band where there is a lack of naturally occurring materials with valuable optical properties. One example are perfect absorbers that are a direct step toward the development of highly sought after detectors and sensing devices. Metasurface absorbers that can be used to substitute for natural materials suffer from poor broadband performance, while those with high absorption and broadband capability typically involve complex fabrication and design and are multilayered. Here, we demonstrate a polarization-insensitive ultrathin (∼λ/6) planar metasurface THz absorber composed of supercells of fractal crosses capable of spanning one optical octave in bandwidth, while still being highly efficient. A sufficiently thick polyimide interlayer produces a unique absorption mechanism based on Salisbury screen and antireflection responses, which lends to the broadband operation. Experimental peak absorption exceeds 93%, while the average absorption is 83% from 2.82 THz to 5.15 THz. This new ultrathin device architecture, achieving an absorption-bandwidth of one optical octave, demonstrates a major advance toward a synthetic metasurface blackbody absorber in the THz ban

Electromagnetic Characterization of Metasurfaces

Electromagnetic characterization of metasurfaces (MSs), electrically/optically thin sheet metamaterials (MMs), is the subject of the current study. Briefly, a MM is a composite material with unusual electromagnetic properties offered by specific response of its constituents and their arrangement. The main goal in this work is to attribute some macroscopic characteristic parameters to MSs.  We first discuss the definitions and present a brief review of the electromagnetic characterization of MMs and MSs. We explain the failures of the traditional characterization approach when applied to MSs. We discuss two known approaches especially suggested for the characterization of MSs in 1990s-2000s.  We continue to introduce a heuristic homogenization model of MSs located on a dielectric interface. Indeed, we derive the general boundary conditions invariant on the polarization of the excitation field. Then, we present the most general algorithm to retrieve the characteristic macroscopic parameters through two-dimensional reflection and transmission dyadics.  We next present two explicit examples of MSs in order to prove the applicability of our theory. The first one is a periodic array of plasmonic nano-spheres while the second one is an array of coupled plasmonic nano-patches positioned in a disordered fashion on a flat surface. We show that our approach works for for both random and periodic MSs. Indeed, the restriction of our theory is a sufficiently small electrical/optical size of a unit cell (area per one particle).  We finally present the main results of the thesis through functional MSs. We theoretically reveal and discuss novel physical effects and various functionalities. We present some discussions on the intrinsically bianisotropic and intrinsically magnetic MSs operating in the visible range. We also discuss the microscopic effect of substrate-induced bianisotropy for a substrated array of plasmonic nano-spheres. Moreover, we reveal the magnetic response within the framework of our homogenization model; i.e., retrieving some magnetic parameters. Furthermore, we obtain the perfect absorbance conditions for different topologies and discuss them in this chapter. Finally, we present a model which explains the different behavior of electric and magnetic resonant modes of MSs in transition from periodic to amorphous arrangements

Metamaterial inspired radar absorbers: Emergence, trends and challenges

The advances in metamaterial science and technology have raised the expectations of camouflage or stealth researchers to one order higher in terms of absorption characteristics. As metamaterial inspired radar absorbing structures are proving themselves as a good candidate with near unity absorption, feasibility towards hardware realization is necessary. Hence an extensive literature survey of metamaterial inspired radar absorbing structure has been carried out and reported in this paper along with the challenges and material issues. The various types of metamaterial structures that can be used as absorber have been provided along with simulation figures. To make the review more useful, graphene and carbon nanotube (CNT) based radar absorbing structures are also included along with their simulation and fabrication techniques