15.2 HUMAN BODY MODEL There is a prime source for electrostatic discharge, which is human. Humans are easy to build up a static charge. The electric circuit to simulate the discharge from a person delivered to the device can be called as human body model and it is a model that is very commonly used for testing the sensitivity of a device to ESD. The capacitance of the human body is used to model the human body discharge. First of all, the capacitance between the soles of the feet and ground is the primary contributor to the body capacitance besides the 50 pF of free space capacitance. In figure 15.2, the feet show 50 pF per foot. As the person going near to other surrounding objects, the additional capacitance of range from 50 to 100 pF may …show more content…
This means that hard ground must be avoided. The minimum impedance, which is 250 kΩ is used to ground a person. The grounded wrist straps must have 1MΩ resistance to the ground. The resistance increases, the time taken form the charge to bleed off the object increases. 15.3.1 Decay Time Decay time is the time taken for the charge to reduce to 37% of its initial value. The decay time can also be known as relaxation time. The decay time is equal to τ = ε/σ where σ is the conductivity and ε is the dielectric constant for the material. The surface resistivity of the material is τ=ερ The decay time can be also be used to measure the resistivity of the material. Materials can be classified based on their surface resistivity. Surface resistivity has the dimensions of ohms per square. The resistivity will be the same no matter what size the square is. Two electrodes that form the opposite sides of a square can be used to measure the surface resistivity. The resistance will be the same regardless of the length of the electrodes as long as the spacing between the electrodes is the same as the length of the electrodes. Surface resistivity can be classified into four categories, as listed in table
However, the TASER has faced massive amounts of bad press and negative views among members of the public. Electro-muscular disruption has become a very controversial issue among society, with some describing it as extremely painful and a form of torture. The true power of the TASER has been witnessed over its short history, causing physical problems, psychological problems and even death. This is becoming more concerning with the TASER becoming the first resort rather than the last resort. With the TASER being carried by an ever-growing population of police officers, alternate forms of less lethal may need to be looked at.
Staff, Mayo Clinic. "Electroconvulsive Therapy (ECT)." Mayo Clinic. 9 July 2010. Web. 10 Nov. 2014.
...ending on the size and tolerances of the patients, the voltages could have ranged anywhere form 70 to 130 volts. As a direct effect from the large amounts of electricity being imposed into the patient’s body they will lose consciousness almost immediately. The shocks sent them in to convulsions or seizures and therefore increased their insulin levels. After a patient regains consciousness, he or she will not remember any of the events of being shocked. (Noyes and Kolb).
The first is electrotactile simulation(3). It uses localized electric currents to stimulate targeted nerves using surface electrodes. This method uses no mechanical parts making it light-weight, energy conserving and less noisy in comparison to other non-invasive tactile stimulation methods. The main disadvantage of electrotactile simulation is reported burning sensations from test subjects. The second type of non-invasive tactile stimulation is vibrotactile stimulation (2), which uses mechanical vibrations on the surface of the skin to convey tactile information using varied vibrations frequency, amplitude and duration. It is best-suited for myoelectric protsthetics as it does not interfere with electric signals. Conversely, it may not be suited for older users as their sensitivity to vibrations might be diminished. The final method for non-invasive tactile stimulation is mechanotactile stimulation, which provides the user with pressure or position feedback. It provides the most natural force sensation out of all of the types of non-invasive tactile stimulation but this method also involves the largest and most energy consuming equipment, making it highly impractical to
Due to the development of safer and less traumatic ways of administering ECT, the treatment has made a comeback, is greatly used, and proves to be effective. B. Historical Context The original use of electricity as a cure for “insanity” dates back to the beginning of the 16th century when electric fish were used to treat headaches. Electroconvulsive therapy on humans originates from research in the 1930’s into the effects of camphor-induced seizures in people with schizophrenia ( Guttmacher, 1994).
This is going to be used as an example to show how the decaying of
Payne, N.A. and Prudic, J. (2009) Electroconvulsive Therapy Part I : A Perspective on the Evolution and Current Practice of ECT Journal of Psychiatric Practice 15(5) pp.346-368
The clinical application of ES can be dated as far back as 1812 when Hartshorne used electricity to promote bone healing in a patient suffering a tibial nonunion, later described in an 1841 publication (Wienke & Dayton, 2011). Research stayed in focus with bone stimulation via ES therapy for many years leading to the US Food and Drug Administration approved labeling electromagnetic devices for treatment of nonunion and delayed union fractures. ES therapy in chronic wound healing became a major research trend in the mid 1960s with a multitude of successful clinical trials to follow (Isseroff & Dahle, 2012). Eventually ES use in treating chronic soft tissue wounds became widely accepted and in 2002 the Centers of Medicare and Medicaid Services approved ES treatment in a clinical setting for certain types of chronic wounds and pressure ulcers. Until 2003, research focus stayed with ES therapy on pressure ulcers but later ...
F Another wire, or exact same properties (Nickel Chrome, thickness 34). mm and length 30cm) was placed on top of the previous wire, in the same position, both straight and flat. F. The power was turned on again and the same procedure was repeated. recording current and voltage at three points on the variable. resistor.
This is know as resistivity. The factors I can investigate are : Ÿ Temperature Ÿ Length Ÿ Cross-sectional area/width Ÿ Material (resistivity) The factor I shall investigate is the length of a wire. Background Knowledge Resistance is when electrons travelling through the wire are impeded by the atoms within the wire. Since the electrons are charge carriers when they collide with the atoms in the wire less pass through.
Since early 2003 the Electrical Inspectorate has been working to raise public awareness of Residual Current Devices (RCDs), with the aim of eventually enforcing the use of these devices as recommended by the standard adopted by the St. Lucia Bureau of Standards for wiring of buildings SLNS/BS 7671: 2001- Requirements for Electrical Installations ¡V IEE Wiring Regulations ¡V Sixteenth Edition. These Regulations though only recently adopted by the Bureau of Standards is the Regulations referred to by the St. Lucia Electricity regulations of 1973 as the standard of wiring of buildings. For a very long time the cost of these devices had proven prohibitive for the enforcement of the requirement. However, it is now believed that safety concerns as it relates to electrical hazards such as fire and electrocution far outweigh the cost of these devices
Where NA is the equivalent number of A transferred per cell during the interval of time t, Q the current quantity supplied to the system during the same time and F is the Faraday constant (96 485 A s mol−1).
L = Length of the conductor(m). A = Area of cross section of the conductor (m2). = the resistivity of the material of which the conductor is made. (Îm) The experimental determination of the resistivity of a material. involves measuring the resistance of a specimen of the material.
These properties can be used for design and analysis of engineering structures, and for developing new materials that better suit a specified use. [8] Tensile tests are simple, relatively inexpensive, and fully standardised. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate and one of the more basic tests is to determine stress – strain relationships. [10] A simple uniaxial test consists of slowly pulling a sample of material in tension until it breaks. The major parameters that describe the stress-strain curve obtained during the tension test are the tensile strength (UTS), yield strength or yield point (σy), elastic modulus (E), percent elongation (∆L%) and the reduction in area (RA%). Toughness, Resilience, Poisson’s ratio (ν) can also be found by the use of this testing technique. 0.2 % off-set method is a commonly used method to determine the yield strength. Yield strength (σy) (0.2%) is found by drawing a parallel line to the elastic region and the point at which this line intersects with the stress-strain curve is set as the yielding point. [9] The following figure is the tensile tester that is used to test the
...reacted to the electrical stimulation. By the 20th Century, doctors used this technology in an experimental treatment of the skin, bone and muscle growth, and healing wounds (according to the Journal of the Advancement in Medicine).