Single displacement reaction
A single-displacement reaction known as a single-replacement reaction, is a reaction by which one element replaces an/other element in a compound. It can be represented generically as: A + B-C → A-C + BThis will most occur if A is more reactive than B, thus giving a more stable product. A and B must be either: Different metals. In either case, when AC and BC are aqueous compounds, C is a spectator ion. In the activity or reactivity series, the metals with the highest propensity to donate their electrons to react are listed first, the most unreactive metals are listed last. Therefore, a metal higher on the list is able to displace anything on the list below it; the order of activity for metals, from most reactive to least reactive, is Li, K, Sr, Na, Ca, Mg, Al, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, H, Sb, As, Bi, Cu, Hg, Ag, Pd, Pt, Au. The halogens with the highest propensity to acquire electrons are the most reactive; the activity series for halogens, from highest to lowest, is F, Cl, Br, I. Due to the free state nature of A and B, all single displacement reactions are oxidation-reduction reactions, where the key event is the movement of electrons from one reactant to another.
When A and B are metals, A is always oxidized and B is always reduced. Since halogens prefer to gain electrons, A is reduced and B is oxidized when A and B represent those elements. A and B may have different charge as ions and therefore some balancing of the equation may be necessary. For example, the reaction between silver nitrate, AgNO3, zinc, Zn, forms silver, Ag, zinc nitrate, Zn2. 2AgNO3 + Zn → 2Ag + Zn2All simple metal with acid reactions are single displacement reactions. For example, the reaction between magnesium, Mg, hydrochloric acid, HCl, forms magnesium chloride, MgCl2, hydrogen, H2. Mg +. A cation is a metal; when it is written in generic symbols, it is written out like this: X + YZ → XZ + YElement X has replaced Y in compound YZ to become a new compound XZ and the free element Y. This is an oxidation–reduction reaction wherein element Y is reduced from a cation into the elemental form and element X is oxidized from the elemental form into a cation; some examples are: Cu + 2 AgNO 3 ⟶ 2 Ag ↓ + Cu 2 Fe + Cu 2 ⟶ Fe 2 + Cu ↓ Ca + 2 H 2 O ⟶ Ca 2 + H 2 ↑ Zn + 2 HCl ⟶ ZnCl 2 + H 2 ↑ Note that if the reactant in elemental form is not the more reactive metal no reaction will occur.
Some examples of this would be the reverse reactions to these: Ag + Cu2 → No reaction Au + HCl → No reaction One anion replaces another. An anion is a nonmetal. Written using generic symbol, it is: A + XY → XA + YElement A has replaced Y to form a new compound XA and the free element Y; this is an oxidation-reduction reaction wherein element A is reduced from the elemental form into an anion and element Y is oxidized from an anion into the elemental form. Some of the few examples that involve halogens are shown here: Cl 2 + 2 NaBr ⟶ 2 NaCl + Br 2 ↓ Br 2 + 2 KI ⟶ 2 KBr + I 2 ↓ Again, the less reactive halogen cannot replace the more reactive halogen: I2 + 2KBr → no reaction Double displacement reaction Substitution reaction Synthesis
Parapsychology is the study of paranormal and psychic phenomena, including telepathy, clairvoyance, near-death experiences, reincarnation, apparitional experiences, other paranormal claims. It is considered to be pseudoscience by a vast majority of mainstream scientists. Parapsychology research is conducted by private institutions in several countries and funded through private donations, the subject never appears in mainstream science journals. Most papers about parapsychology are published in a small number of niche journals. Parapsychology has been criticised for continuing investigation despite being unable to provide convincing evidence for the existence of any psychic phenomena after more than a century of research; the term parapsychology was coined in 1889 by philosopher Max Dessoir as the German "parapsychologie." It was adopted by J. B. Rhine in the 1930s as a replacement for the term psychical research in order to indicate a significant shift toward experimental methodology and academic discipline.
The term originates from the Greek: παρά para meaning "alongside", psychology. In parapsychology, psi is the unknown factor in extrasensory perception and psychokinesis experiences, not explained by known physical or biological mechanisms; the term is derived from the Greek ψ psi, 23rd letter of the Greek alphabet and the initial letter of the Greek ψυχή psyche, "mind, soul". The term was coined by biologist Berthold P. Wiesner, first used by psychologist Robert Thouless in a 1942 article published in the British Journal of Psychology; the Parapsychological Association divides psi into two main categories: psi-gamma for extrasensory perception and psi-kappa for psychokinesis. In popular culture, "psi" has become more and more synonymous with special psychic, "psionic" abilities and powers. In 1853, the chemist Robert Hare reported positive results. Other researchers such as Frank Podmore highlighted flaws in his experiments, such as lack of controls to prevent trickery. Agenor de Gasparin conducted early experiments into table-tipping.
Over a period of five months in 1853 he declared the experiments a success being the result of an "ectenic force". Critics noted. For example, the knees of the sitters may have been employed to move the table and no experimenter was watching above and below the table simultaneously; the German astrophysicist Johann Karl Friedrich Zöllner tested the medium Henry Slade in 1877. According to Zöllner some of the experiments were a success. However, flaws in the experiments were discovered and critics have suggested that Slade was a fraud who performed trickery in the experiments; the Society for Psychical Research was founded in London in 1882. Its formation was the first systematic effort to organize scientists and scholars to investigate paranormal phenomena. Early membership included philosophers, scientists and politicians, such as Henry Sidgwick, Arthur Balfour, William Crookes, Rufus Osgood Mason and Nobel Laureate Charles Richet. Presidents of the Society included, in addition to Richet, Eleanor Sidgwick and William James, subsequently Nobel Laureates Henri Bergson and Lord Rayleigh, philosopher C. D. Broad.
Areas of study included telepathy, Reichenbach's phenomena, apparitions and the physical aspects of Spiritualism such as table-tilting and apportation. In the 1880s the Society investigated apparitional hallucinations in the sane. Among the first important works was the two-volume publication in 1886, Phantasms of the Living, criticized by scholars. In 1894, the Census of Hallucinations was published which sampled 000 people. Out of these, 1, 684 persons admitted to having experienced a hallucination of an apparition; the SPR became the model for similar societies in other European countries and the United States during the late 19th century. Early clairvoyance experiments were reported in 1884 by Charles Richet. Playing cards were enclosed in envelopes and a subject put under hypnosis attempted to identify them; the subject was reported to have been successful in a series of 133 trials but the results dropped to chance level when performed before a group of scientists in Cambridge. J. M. Peirce and E. C.
Pickering reported a similar experiment in which they tested 36 subjects over 23,384 trials which did not obtain above chance scores. In 1881, Eleanor Sidgwick revealed the fraudulent methods that spirit photographers such as Édouard Isidore Buguet, Frederic Hudson and William H. Mumler had utilized. During the late nineteenth century many fraudulent mediums were exposed by SPR investigators. Due to the support of psychologist William James, the American Society for Psychical Research opened its doors in Boston in 1885, moving to New York City in 1905 under the leadership of James H. Hyslop. Notable cases investigated by Walter Franklin Prince of the ASPR in the early 20th century included Pierre L. O. A. Keeler, the Great Amherst Mystery and Patience Worth. In 1911, Stanford University became the first academic institution in the United States to study extrasensory perception and psychokinesis in a laboratory setting; the effort was headed by psychologist John Edgar Coover, was supported by funds donated by Thomas Welton Stanford, brother of the university's founder.
After conducting 10,000 experiments, Coover concluded "statistical treatments of the data fail to reveal any cause beyond chance."In 1930, Duke University became the second major U. S. academic institution to engage in psychokinesis in the laboratory. Under the guidance of psychologist William McDougall, with the
Angular displacement of a body is the angle in radians through which a point revolves around a centre or line has been rotated in a specified sense about a specified axis. When a body rotates about its axis, the motion cannot be analyzed as a particle, as in circular motion it undergoes a changing velocity and acceleration at any time; when dealing with the rotation of a body, it becomes simpler to consider the body itself rigid. A body is considered rigid when the separations between all the particles remains constant throughout the body's motion, so for example parts of its mass are not flying off. In a realistic sense, all things can be deformable, however this impact is minimal and negligible, thus the rotation of a rigid body over a fixed axis is referred to as rotational motion. In the example illustrated to the right, a particle or body P is at a fixed distance r from the origin, O, rotating counterclockwise, it becomes important to represent the position of particle P in terms of its polar coordinates.
In this particular example, the value of θ is changing, while the value of the radius remains the same.. As the particle moves along the circle, it travels an arc length s, which becomes related to the angular position through the relationship:- s = r θ Angular displacement may be measured in radians or degrees. Using radians provides a simple relationship between distance traveled around the circle and the distance r from the centre. Θ = s r For example, if a body rotates 360° around a circle of radius r, the angular displacement is given by the distance traveled around the circumference -, 2πr - divided by the radius: θ = 2 π r r which simplifies to: θ = 2 π. Therefore, 1 revolution is 2 π radians; when a particle travels from point P to point Q over δ t, as it does in the illustration to the left, the radius of the circle goes through a change in angle Δ θ = θ 2 − θ 1 which equals the angular displacement. In three dimensions, angular displacement is an entity with a magnitude; the direction specifies the axis of rotation, which always exists by virtue of the Euler's rotation theorem.
This entity is called an axis-angle. Despite having direction and magnitude, angular displacement is not a vector because it does not obey the commutative law for addition; when dealing with infinitesimal rotations, second order infinitesimals can be discarded and in this case commutativity appears. Several ways to describe angular displacement exist, like rotation matrices or Euler angles. See charts on SO for others. Given that any frame in the space can be described by a rotation matrix, the displacement among them can be described by a rotation matrix. Being A 0 and A f two matrices, the angular displacement matrix between them can be obtained as Δ A = A f. A 0 − 1; when this product is performed having a small difference between both frames we will obtain a matrix close to the identity. In the limit, we will have an infinitesimal rotation matrix. An infinitesimal angular displacement is an infinitesimal rotation matrix: As any rotation matrix has a single real eigenvalue, +1, this eigenvalue shows the rotation axis.
Its module can be deduced from the value of the infinitesimal rotation. The shape of the matrix is like this: A = We can introduce here the infinitesimal angular displacement tensor or rotation generator associated: d Φ = ( 0 − d ϕ z d ϕ y ( t
A hull is the watertight body of a ship or boat. The hull may open at the top, or it may be or covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast; the line where the hull meets the water surface is called the waterline. There is a wide variety of hull types that are chosen for suitability for different usages, the hull shape being dependent upon the needs of the design. Shapes range from a nearly perfect box in the case of scow barges, to a needle-sharp surface of revolution in the case of a racing multihull sailboat; the shape is chosen to strike a balance between cost, hydrostatic considerations and special considerations for the ship's role, such as the rounded bow of an icebreaker or the flat bottom of a landing craft. In a typical modern steel ship, the hull will have watertight decks, major transverse members called bulkheads. There may be intermediate members such as girders and webs, minor members called ordinary transverse frames, frames, or longitudinals, depending on the structural arrangement.
The uppermost continuous deck may be called the "upper deck", "weather deck", "spar deck", "main deck", or "deck". The particular name given depends on the context—the type of ship or boat, the arrangement, or where it sails. In a typical wooden sailboat, the hull is constructed of wooden planking, supported by transverse frames and bulkheads, which are further tied together by longitudinal stringers or ceiling, but not always there is a centerline longitudinal member called a keel. In fiberglass or composite hulls, the structure may resemble wooden or steel vessels to some extent, or be of a monocoque arrangement. In many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb or other material; the earliest proper hulls were built by the Ancient Egyptians, who by 3000 BC knew how to assemble wooden planks into ahull. See also: Hull Hulls come in many varieties and can have composite shape, but are grouped as follows: Chined and Hard-chined.
Examples are the flat-bottom, v-bottom, multi-bottom hull. These types have at least one pronounced knuckle throughout most of their length. Moulded, round soft-chined; these hull shapes all have smooth curves. Examples are the round bilge, semi-round bilge, s-bottom hull. Displacement hull: here the hull is supported or predominantly by buoyancy. Vessels that have this type of hull travel through the water at a limited rate, defined by the waterline length, they are though not always, heavier than planing types. Planing hull: here, the planing hull form is configured to develop positive dynamic pressure so that its draft decreases with increasing speed; the dynamic lift reduces the wetted surface and therefore the drag. They are sometimes flat-bottomed, sometimes V-bottomed and more round-bilged; the most common form is to have at least one chine, which makes for more efficient planing and can throw spray down. Planing hulls are more efficient at higher speeds, although they still require more energy to achieve these speeds.
An effective planing hull must be as light as possible with flat surfaces that are consistent with good sea keeping. Sail boats that plane must sail efficiently in displacement mode in light winds. Semi-displacement, or semi-planing: here the hull form is capable of developing a moderate amount of dynamic lift. At present, the most used form is the round bilge hull. In the inverted bell shape of the hull, with a smaller payload the waterline cross-section is less, hence the resistance is less and the speed is higher. With a higher payload the outward bend provides smoother performance in waves; as such, the inverted bell shape is a popular form used with planing hulls. A chined hull consists of straight, tall, long, or short plates, timbers or sheets of ply, which are set at an angle to each other when viewed in transverse section; the traditional chined hull is a simple hull shape because it works with only straight planks bent into a curve. These boards are bent lengthwise. Plywood chined boats made of 8' x 4' sheets have most bend along the long axis of the sheet.
Only thin ply 3–6 mm can be shaped into a compound bend. Most home-made constructed boats are chined hull boats. Mass-produced chine powerboats are made of sprayed chop strand fibreglass over a wooden mold; the Cajun "pirogue" is an example of a craft with hard chines. Benefits of this type of hull is the low production cost and the flat bottom, making the boat faster at planing. Sail boats with chined hull make use of a dagger keel. Chined hulls may have one of three shapes: Flat-bottom chined hulls Multi-chined hulls V-bottom chined hulls. Sometimes called hard chine; each of these chine hulls use. The flat bottom hull has high initial stability but high drag. To counter the high drag hull forms are narrow and sometimes tapered at bow and stern; this leads to poor stability. This is countered by using heavy interior ballast on sailing versions, they are best suited to sheltered inshore waters. Early racing power boats were flat aft; this produced maximum lift and a smooth,fast ride in flat water but this hull form is unsettled in waves.
The multi chine h
Electric displacement field
In physics, the electric displacement field, denoted by D, is a vector field that appears in Maxwell's equations. It accounts for the effects of free and bound charge within materials. "D" stands as in the related concept of displacement current in dielectrics. In free space, the electric displacement field is equivalent to flux density, a concept that lends understanding to Gauss's law. In the International System of Units, it is expressed in units of coulomb per meter squared. In a dielectric material, the presence of an electric field E causes the bound charges in the material to separate, inducing a local electric dipole moment; the electric displacement field D is defined as D ≡ ε 0 E + P, where ε 0 is the vacuum permittivity, P is the density of the permanent and induced electric dipole moments in the material, called the polarization density. The displacement field satisfies Gauss's law in a dielectric: ∇ ⋅ D = ρ − ρ b = ρ f Electrostatic forces on ions or electrons in the material are governed by the electric field E in the material via the Lorentz Force.
D is not determined by the free charge. As E has a curl of zero in electrostatic situations, it follows that ∇ × D = ∇ × P The effect of this equation can be seen in the case of an object with a "frozen in" polarization like a bar electret, the electric analogue to a bar magnet. There is no free charge in such a material, but the inherent polarization gives rise to an electric field, demonstrating that the D field is not determined by the free charge; the electric field is determined by using the above relation along with other boundary conditions on the polarization density to yield the bound charges, which will, in turn, yield the electric field. In a linear, isotropic dielectric with instantaneous response to changes in the electric field, P depends linearly on the electric field, P = ε 0 χ E, where the constant of proportionality χ is called the electric susceptibility of the material, thus D = ε 0 E = ε E where ε = ε0 εr is the permittivity, εr = 1 + χ the relative permittivity of the material.
In linear, isotropic media, ε is a constant. However, in linear anisotropic media it is a tensor, in nonhomogeneous media it is a function of position inside the medium, it may depend upon the electric field and have a time dependent response. Explicit time dependence can arise. A different form of time dependence can arise in a time-invariant medium, as there can be a time delay between the imposition of the electric field and the resulting polarization of the material. In this case, P is a convolution of the impulse response susceptibility χ and the electric field E; such a convolution takes on a simpler form in the frequency domain: by Fourier transforming the relationship and applying the convolution theorem, one obtains the following relation for a linear time-invariant medium: D = ε E, where ω is the frequency of the applied field. The constraint of causality leads to the Kramers–Kronig relations, which place limitations upon the form of the frequency dependence; the phenomenon of a frequency-dependent permittivity is an example of material dispersion.
In fact, all physical materials have some material dispersion because they cannot respond instantaneously to applied fields, but for many problems the frequency-dependence of ε can be neglected. At a boundary, ⋅ n ^ = D 1, ⊥ − D 2, ⊥ = σ f, where σf is the free charge density and the unit normal n ^ points in the direction from medium 2 to medium 1. Gauss's law was formulated by Carl Friedrich Gauss in 1835, but was not published until 1867, meaning that the formulation and use of D were not earlier than 1835, not earlier than the 1860s; the earliest known use of the term is from the year 1864, in James Clerk Maxwell's paper A Dynamical Theory of the Electromagnetic Field. Maxwell used calculus to exhibit Mic
In fluid mechanics, displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can be measured, from this, the volume of the immersed object can be deduced. An object that sinks displaces an amount of fluid equal to the object's volume, thus buoyancy is expressed through Archimedes' principle, which states that the weight of the object is reduced by its volume multiplied by the density of the fluid. If the weight of the object is less than this displaced quantity, the object floats; the amount of fluid displaced is directly related to its volume. In the case of an object that sinks, the volume of the object is displaced. In the case of an object that floats, the amount of fluid displaced will be equal in weight to the displacing object. Archimedes' principle, a physical law of buoyancy, states that any body or submerged in a fluid at rest is acted upon by an upward, or buoyant, force the magnitude of, equal to the weight of the fluid displaced by the body.
The volume of displaced fluid is equivalent to the volume of an object immersed in a fluid or to that fraction of the volume below the surface of an object submerged in a liquid. The weight of the displaced portion of the fluid is equivalent to the magnitude of the buoyant force; the buoyant force on a body floating in a liquid or gas is equivalent in magnitude to the weight of the floating object and is opposite in direction. If the weight of an object is less than that of the displaced fluid, the object rises, as in the case of a block of wood, released beneath the surface of water or a helium-filled balloon, let loose in the air. An object heavier than the amount of the fluid it displaces, though it sinks when released, has an apparent weight loss equal to the weight of the fluid displaced. In fact, in some accurate weighing, a correction must be made in order to compensate for the buoyancy effect of the surrounding air; the buoyant force, which always opposes gravity, is caused by gravity.
Fluid pressure increases with depth because of the weight of the fluid above. This increasing pressure applies a force on a submerged object; the result is buoyancy. This method can be used to measure the volume of a solid object if its form is not regular. Several methods of such measuring exist. In one case the increase of liquid level is registered. In the second case, the object is immersed into a vessel full of liquid; the spilled liquid is collected and its volume measured. In the third case, the object is suspended under the surface of the liquid and the increase of weight of the vessel is measured; the increase in weight is equal to the amount of liquid displaced by the object, the same as the volume of the suspended object times the density of the liquid. The concept of Archimedes' principle is that an object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object; the weight of the displaced fluid can be found mathematically. The mass of the displaced fluid can be expressed in terms of the density and its volume, m = ρV.
The fluid displaced has a weight W = mg. Therefore, the weight of the displaced fluid can be expressed; the weight of an object or substance can be measured by floating a sufficiently buoyant receptacle in the cylinder and noting the water level. After placing the object or substance in the receptacle, the difference in weight of the water level volumes will equal the weight of the object. Displacement
Positive displacement meter
A positive displacement meter is a type of flow meter that requires fluid to mechanically displace components in the meter in order for flow measurement. Positive displacement flow meters measure the volumetric flow rate of a moving fluid or gas by dividing the media into fixed, metered volumes. A basic analogy would be holding a bucket below a tap, filling it to a set level quickly replacing it with another bucket and timing the rate at which the buckets are filled. With appropriate pressure and temperature compensation, the mass flow rate can be determined; these devices consist of a chamber that obstructs the media flow and a rotating or reciprocating mechanism that allows the passage of fixed-volume amounts. The number of parcels that pass through the chamber determines the media volume; the rate of revolution or reciprocation determines the flow rate. There are two basic types of positive displacement flow meters. Sensor-only systems or transducers are switch-like devices that provide electronic outputs for processors, controllers, or data acquisition systems.
Complete sensor systems provide additional capabilities such as an integral display and/or user interface. For both types of positive displacement flow meters, performance specifications include the minimum and maximum measurable flow rate, operating pressure, temperature range, maximum allowable material viscosity, connection size, percent accuracy. Suppliers indicate whether devices are designed to measure gas. A screw flometer is composed of a set of screws which form with the internal structure of the flowmeters' casing a measurement chamber; the screw will get into rotation thanks to the medium passing through the device, which will be transfered by the-said screws from one end to the other end of the measuring device. For this to be done, the pressure drop is essential and seen as a "necessary evil"; this rotation can be recorded by a sensor which, combined with the Process Unit, will be able to deliver a measurement according to the flowrate and size of the measurement chamber. Screw flowmeters are well-acknowledged for their excellent linearity, excellent repeatbility and accuracy.
They have the propensity to be used as metrological international reference and/or standard by metrological institutes, due to their outstanding features and reliability. Thanks to screw meters, Public & Independent Institutes of Metrology worldwide can compare their respective work, facilities, or calibrate other flowmeters or compare flowmeters' performance according to different measurement principles. List of Public & Independent Institutes of Metrology using screw flow meters as international reference and/or standard: Australia, Belgium, Czech Republic, France, Japan, Scotland, Switzerland, Taiwan R. O. C; the Netherlands, The United Kingdom, Vietnam Each piston is mechanically or magnetically operated to fill a cylinder with the fluid and discharge the fluid. Each stroke represents a finite measurement of the fluid. Gear flow meters rely on internal gears rotating as fluid passes through them. There are various types of gear meters named for the shape of the internal components Oval GearTwo rotating oval gears with synchronized teeth “squeeze” a finite amount of fluid through the meter for each revolution.
With oval gear flow meters, two oval gears or rotors are mounted inside a cylinder. As the fluid flows through the cylinder, the pressure of the fluid causes the rotors to rotate; as flow rate increases, so does the rotational speed of the rotors. Helical GearHelical gear flow meters get their name from the shape of their rotors; these rotors resemble the shape of a helix, a spiral-shaped structure. As the fluid flows through the meter, it enters the compartments in the rotors, causing the rotors to rotate. Flowrate is calculated from the speed of rotation. A disk mounted on a sphere is “wobbled” about an axis by the fluid flow and each rotation represents a finite amount of fluid transferred. A nutating disc flow meter has a round disc mounted on a spindle in a cylindrical chamber. By tracking the movements of the spindle, the flow meter determines the number of times the chamber traps and empties fluid; this information is used to determine flow rate. A rotating impeller containing two or more vanes divides the spaces between the vanes into discrete volumes and each rotation is counted.
Flow = volume of measuring chamber* R. P. M.*4 Fluid is drawn into the inlet side of an oscillating diaphragm and dispelled to the outlet. The diaphragm oscillating cycles are counted to determine the flow rate. Positive displacement flowmeters are accurate and have high turndown, they can be used in viscous and corrosive fluids and require no straight runs of pipe for fluid flow stream conditioning though pressure drop can be an issue. They are used in the custody transfer of oils and liquid fluids and are applied on residential home natural gas and water metering. A diaphragm meter, with which most homes are equipped, is an example of a positive displacement meter; this type of meter is appealing in certain custody transfer flow applications where it is critical that the metering be functional in order for any flow to take place. PD flowmeters, with internal wiping seals, produce the highest differential pressure of all the flowmeter types. Meters that rely on a liqui