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Engineering is the design, analysis, and/or construction of works for practical purposes. The Engineers' Council for Professional Development, also known as ECPD, (later ABET ) defines Engineering as: "The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property." One who practices engineering is called an engineer, and those licensed to do so have formal designations such as Professional Engineer , Chartered Engineer or Incorporated Engineer. The broad discipline of engineering encompasses a range of specialized subdisciplines that focus on the issues associated with developing a specific kind of product, or using a specific type of technology.

Chemical engineering is the branch of engineering that deals with the application of physical science (e.g. chemistry and physics), with mathematics, to the process of converting raw materials or chemicals into more useful or valuable forms. As well as producing useful materials, chemical engineering is also concerned with pioneering valuable new materials and techniques; an important form of research and development. A person employed in this field is called a chemical engineer.Chemical engineering largely involves the design and maintenance of chemical processes for large-scale manufacture. Chemical engineers in this branch are usually employed under the title of process engineer. The development of the large-scale processes characteristic of industrialized economies is a feat of chemical engineering, not chemistry. Indeed, chemical engineers are responsible for the availability of the modern high-quality materials that are essential for running an industrial economy.

Modern chemical engineering

The modern discipline of chemical engineering encompasses much more than just process engineering. Chemical engineers are now engaged in the development and production of a diverse range of products, as well as in commodity and specialty chemicals. These products include high performance materials needed for aerospace, automotive, biomedical, electronic, environmental and space and military applications. Examples include ultra-strong fibers, fabrics, adhesives and composites for vehicles, bio-compatible materials for implants and prosthetics, gels for medical applications, pharmaceuticals, and films with special dielectric, optical or spectroscopic properties for opto-electronic devices. Additionally, chemical engineering is often intertwined with biology and biomedical engineering. Many chemical engineers work on biological projects such as understanding biopolymers (proteins) and mapping the human genome.

Biomedical engineering

Biomedical engineering (BME) is the application of engineering principles and techniques to the medical field. It combines the design and problem solving skills of engineering with the medical and biological science to help improve patient health care and the quality of life of healthy individuals.As a relatively new discipline, much of the work in biomedical engineering consists of research and development, covering an array of fields: bioinformatics, medical imaging, image processing, physiological signal processing, biomechanics, biomaterials and bioengineering, systems analysis, 3-D modeling, etc. Examples of concrete applications of biomedical engineering are the development and manufacture of biocompatible prostheses, medical devices, diagnostic devices and imaging equipment such as MRIs and EEGs, and pharmaceutical drugs.

Tissue engineering

One of the goals of tissue engineering is to create artificial organs for patients that need organ transplants. Biomedical engineers are currently researching methods of creating such organs. In one case bladders have been grown in lab and transplanted successfully into patients. Bioartificial organs, which utilize both synthetic and biological components, are also a focus area in research, such as with hepatic assist devices that utilize liver cells within an artificial bioreactor construct

Safety engineering

Safety engineering is an applied science strongly related to systems engineering and the subset System Safety Engineering. Safety engineering assures that a life-critical system behaves as needed even when pieces fail.

In the real world the term "safety engineering" refers to any act of accident prevention by a person qualified in the field. Safety engineering is often reactionary to adverse events, also described as "incidents", as reflected in accident statistics. This arises largely because of the complexity and difficulty of collecting and analysing data on "near misses".

Increasingly, the importance of a safety review is being recognised as an important risk management tool. Failure to identify risks to safety, and the according inability to address or "control" these risks, can result in massive costs, both human and economic. The multidisciplinary nature of safety engineering means that a very broad array of professionals are actively involved in accident prevention or safety engineering.

The majority of those practicing safety engineering are employed in industry to keep workers safe on a day to day basis. See the American Society of Safety Engineers publication Scope and Function of the Safety Profession.

Safety engineers distinguish different extents of defective operation: A "failure" is "the inability of a system or component to perform its required functions within specified performance requirements", while a "fault" is "a defect in a device or component, for example: a short circuit or a broken wire".^[1] System-level failures are caused by lower-level faults, which are ultimately caused by basic component faults. (Some texts reverse or confuse these two terms. The unexpected failure of a device that was operating within its design limits is a "primary failure", while the expected failure of a component stressed beyond its design limits is a "secondary failure". A device which appears to malfunction because it has responded as designed to a bad input is suffering from a "command fault".^[2] A "critical" fault endangers one or a few people. A "catastrophic" fault endangers, harms or kills a significant number of people.

Safety engineers also identify different modes of safe operation: A "probabilistically safe" system has no single point of failure, and enough redundant sensors, computers and effectors so that it is very unlikely to cause harm (usually "very unlikely" means, on average, less than one human life lost in a billion hours of operation). An inherently safe system is a clever mechanical arrangement that cannot be made to cause harm ??obviously the best arrangement, but this is not always possible. A fail-safe system is one that cannot cause harm when it fails. A "fault-tolerant" system can continue to operate with faults, though its operation may be degraded in some fashion.

These terms combine to describe the safety needed by systems: For example, most biomedical equipment is only "critical", and often another identical piece of equipment is nearby, so it can be merely "probabilistically fail-safe". Train signals can cause "catastrophic" accidents (imagine chemical releases from tank-cars) and are usually "inherently safe". Aircraft "failures" are "catastrophic" (at least for their passengers and crew) so aircraft are usually "probabilistically fault-tolerant". Without any safety features, nuclear reactors might have "catastrophic failures", so real nuclear reactors are required to be at least "probabilistically fail-safe", and some such as pebble bed reactors are "inherently fault-tolerant".