Base isolation, also known as seismic or base isolation system, is a collection of structural elements which should substantially decouple a superstructure from its substructure resting on a shaking ground thus protecting a building or non-building structure's integrity.
Base isolation is the most powerful tool of the earthquake engineering pertaining to the passive structural vibration control technologies. It is meant to enable a building or non-building structure to survive a potentially devastating seismic impact through a proper initial design or subsequent modifications. In some cases, application of base isolation can raise both a structure's seismic performance and its seismic sustainability considerably.
Base isolation system consists of isolation units with or without isolation components, where:
1. Isolation units are the basic elements of base isolation system which are intended to provide the mentioned decoupling effect to a building or non-building structure.
2. Isolation components are the connections between isolation units and their parts having no decoupling effect of their own.
By their response to an earthquake impact, all isolation units may be divided into two basic categories: shear units and sliding units. The first evidence of architects using the principle of base isolation for earthquake protection was discovered in Pasargadae, a city in ancient Persia, now Iran: it goes back to VI century BC.
Bending
In engineering mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to an axis of the element. The structural element is assumed to be such that at least one of its dimensions is a small fraction, typically 1/10 or less, of the other two. When the length is considerably larger than the width and the thickness, the element is called a beam. A closet rod sagging under the weight of clothes on clothes hangers is an example of a beam experiencing bending. On the other hand, a shell is a structure where the length and the width are of the same order of magnitude but the thickness of the element is considerably smaller. The curved surface of an open parachute is an example of a shell experiencing bending.
Biomechanics
Biomechanics (Greek: ß??? + µ??a???? = ß??µ??a????, Greece: eµß??µ??a???? because ß??µ??a???? = industrial) is the application of mechanical principles to living organisms. This includes bioengineering, the research and analysis of the mechanics of living organisms and the application of engineering principles to and from biological systems. This research and analysis can be carried forth on multiple levels, from the molecular, wherein biomaterials such as collagen and elastin are considered, all the way up to the tissue and organ level. Some simple applications of Newtonian mechanics can supply correct approximations on each level, but precise details demand the use of continuum mechanics.
Aristotle wrote the first book on biomechanics, De Motu Animalium, or On the Movement of Animals. He not only saw animals' bodies as mechanical systems, but pursued questions such as the physiological difference between imagining performing an action and actually doing it. Some simple examples of biomechanics research include the investigation of the forces that act on limbs, the aerodynamics of bird and insect flight, the hydrodynamics of swimming in fish, and locomotion in general across all forms of life, from individual cells to whole organisms. The biomechanics of human beings is a core part of kinesiology.
The application of biomechanical principles to plants and plant organs has developed into the sister field of Plant biomechanics. The many strands of plant biomechanics are described in a text book on the subject by Karl Niklas Plant Biomechanics: An Engineering Approach to Plant Form and Function.
Applied mechanics, most notably thermodynamics and continuum mechanics, and mechanical engineering disciplines such as fluid mechanics and solid mechanics, play prominent roles in the study of biomechanics. By applying the laws and concepts of physics, biomechanical mechanisms and structures can be simulated and studied. Such concepts are found in the field of Sports Biomechanics where we apply the laws of mechanics and physics to human performance in order to gain a greater understanding of performance in athletic events through modeling, computer simulation, stimulation, gesticulation, mastication and measurement. Elements of Mechanical Engineering (e.g. strain gauges), Electrical Engineering (e.g. digital filtering), Physics/Dynamics (e.g. moments of inertia), Computer Science (e.g. numerical methods) and Clinical Neurophysiology (e.g. surface EMG) are common methods used for the analysis.
Relevant mathematical tools include linear algebra, differential equations, vector and tensor calculus, numerics and computational techniques such as the finite element method.
The study of biomaterials is of crucial importance to biomechanics. For example, the various tissues within the body's organs, such as skin, bone, and arteries each possess unique material properties. The passive mechanical response of a particular tissue can be attributed to characteristics of the various proteins, such as elastin and collagen, living cells, ground substances such as proteoglycans, and the orientations of fibers within the tissue. For example, if human skin were largely composed of a protein other than collagen, many of its mechanical properties, such as its elastic modulus, would be different.
It has been shown that applied loads and deformations can affect the properties of living tissue. There is much research in the field of growth and remodeling as a response to applied loads. For example, the effects of elevated blood pressure on the mechanics of the arterial wall, the behavior of cardiomyocytes within a heart with a cardiac infarct, and bone growth in response to exercise, and the acclimative growth of plants in response to wind movement, have been widely regarded as instances in which living tissue is remodelled as a direct consequence of applied loads.
Chemistry, molecular biology, and cell biology have much to offer in the way of explaining the active and passive properties of living tissues. For example, in muscle contractions, the binding of myosin to actin is based on a biochemical reaction involving calcium ions and ATP.
Bore gauge
A bore gauge is a convenient term for the measuring or transfer tools that are used in the process of accurately measuring holes.
These are a range of gauges that are used to measure a bore's size, by transferring the internal dimension to a remote measuring tool. They are a direct equivalent of inside calipers and require the operator to develop the correct feel to obtain repeatable results.
The gauges are locked by twisting the knurled end of the handles, this action is performed to exert a small amount of friction on the telescopic portions of the gauge (the smaller diameter rods found at the T head of the gauge). Once gently locked to a size slightly larger than the bore, the gauges are inserted at an angle to the bore and slowly brought to align themselves radially, across the hole. This action compresses the two anvils where they remain locked at the bores dimension after being withdrawn.
The gauge is then removed and measured with the aid of a micrometer or vernier caliper.
Buckling
In engineering, buckling is a failure mode characterized by a sudden failure of a structural member subjected to high compressive stresses, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding. This mode of failure is also described as failure due to elastic instability. Mathematical analysis of buckling makes use of an axial load eccentricity that introduces a moment, which does not form part of the primary forces to which the member is subjected.
Biological Engineering
Biological Engineering or bioengineering (including biological systems engineering) is the application of engineering principles to address challenges in the fields of biology and medicine. Biological engineering applies principles to the full spectrum of living systems, including molecular biology, biochemistry, microbiology, pharmacology, protein chemistry, cytology, immunology, neurobiology and neuroscience. As a study, it encompasses biomedical engineering and it is related to biotechnology. It deals with disciplines of product design, sustainability and analysis to improve and focus utilization of biological systems.
The word was bioengineering was coined by British scientist and broadcaster Heinz Wolff in 1954. [1] The term bioengineering is also used to describe the use of vegetation in civil engineering construction. The term bioengineering may also be applied to environmental modifications such as surface soil protection, slope stabilisation, watercourse and shoreline protection, windbreaks, vegetation barriers including noise barriers and visual screens, and the ecological enhancement of an area.
Biological Engineering employs knowledge and expertise from a number of pure and applied sciences, such as mass and heat transfer, kinetics, biocatalysts, biomechanics, bioinformatics, separation and purification processes, bioreactor design, surface science, fluid mechanics, thermodynamics, and polymer science. It is used in the design of medical devices, diagnostic equipment, biocompatible materials, and other important medical needs that improve the living standards of societies.
Biological Engineers or bioengineers are engineers who use the principles of biology and the tools of engineering to create usable, tangible products. In general, biological engineers attempt to either mimic biological systems in order to create products or modify and control biological systems so that they can replace, augment, or sustain chemical and mechanical processes. Bioengineers can apply their expertise to other applications of engineering and biotechnology, including genetic modification of plants and microorganisms, bioprocess engineering, and biocatalysis.
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