Every person with an electronics background will be familiar with the three fundamental circuit elements - the resistor, the capacitor, and the inductor. These three elements are defined by the relation between two of the four fundamental circuit variables -
current, voltage, charge and flux.
In 1971, Leon Chua reasoned on the grounds of symmetry that there should be a fourth fundamental circuit element which gives the relationship between flux and charge. He named this circuit element the memristor, which is short for memory resistor. In May 2008, researchers at HP Labs published a paper announcing a model for the physical realization of the memristor.
It is proposed that memory storage devices that has very high data density and computers that require no time for boot up can be developed using memristor based hardware. A new physical quantity which is also introduced associated with memristor. It also solves someunexplained voltage current characteristics observed in certain materials at atomic levels.
Resistive RAMs are non-volatile RAMs and with the help of Nanomaterials we can make them faster in switching speed,smaller in size and store information in "Terabit" scale or more.In a nutshell "a revolution in the market of memory devices".
Memristors are basically a fourth class of electrical circuit, joining the resistor, the capacitor, and the inductor, that exhibit their unique properties primarily at the nanoscale. Theoretically, Memristors, a concatenation of “memory resistors”, are a type of passive circuit elements that maintain a relationship between the time integrals of current and voltage across
a two terminal element. Thus, a memristors resistance varies according to a devices memristance function, allowing, via tiny read charges, access to a “history” of applied voltage. The material implementation of memristive effects can be determined in part by the presence of hysteresis (an accelerating rate of change as an object moves from one state to another) which, like many other non-linear “anomalies” in contemporary circuit theory, turns out to be less an anomaly than a fundamental property of passive circuitry.
Every person with an electronics background will be familiar with the three fundamental circuit elements - the resistor, the capacitor, and the inductor. These three elements are defined by the relation between two of the four fundamental circuit variables -
current, voltage, charge and flux.
In 1971, Leon Chua reasoned on the grounds of symmetry that there should be a fourth fundamental circuit element which gives the relationship between flux and charge. He named this circuit element the memristor, which is short for memory resistor. In May 2008, researchers at HP Labs published a paper announcing a model for the physical realization of the memristor.
It is proposed that memory storage devices that has very high data density and computers that require no time for boot up can be developed using memristor based hardware. A new physical quantity which is also introduced associated with memristor. It also solves someunexplained voltage current characteristics observed in certain materials at atomic levels.
Resistive RAMs are non-volatile RAMs and with the help of Nanomaterials we can make them faster in switching speed,smaller in size and store information in "Terabit" scale or more.In a nutshell "a revolution in the market of memory devices".
Memristors are basically a fourth class of electrical circuit, joining the resistor, the capacitor, and the inductor, that exhibit their unique properties primarily at the nanoscale. Theoretically, Memristors, a concatenation of “memory resistors”, are a type of passive circuit elements that maintain a relationship between the time integrals of current and voltage across
a two terminal element. Thus, a memristors resistance varies according to a devices memristance function, allowing, via tiny read charges, access to a “history” of applied voltage. The material implementation of memristive effects can be determined in part by the presence of hysteresis (an accelerating rate of change as an object moves from one state to another) which, like many other non-linear “anomalies” in contemporary circuit theory, turns out to be less an anomaly than a fundamental property of passive circuitry.
you can be friend with me on orkut
"mangalforyou@gmail.com" : i belive in sharing the knowledge so please send project reports ,seminar and ppt. to me .
(If visualization is slow, please try downloading the file.)
Part 2 of a tutorial given in the Brazilian Physical Society meeting, ENFMC. Abstract: Density-functional theory (DFT) was developed 50 years ago, connecting fundamental quantum methods from early days of quantum mechanics to our days of computer-powered science. Today DFT is the most widely used method in electronic structure calculations. It helps moving forward materials sciences from a single atom to nanoclusters and biomolecules, connecting solid-state, quantum chemistry, atomic and molecular physics, biophysics and beyond. In this tutorial, I will try to clarify this pathway under a historical view, presenting the DFT pillars and its building blocks, namely, the Hohenberg-Kohn theorem, the Kohn-Sham scheme, the local density approximation (LDA) and generalized gradient approximation (GGA). I would like to open the black box misconception of the method, and present a more pedagogical and solid perspective on DFT.
Theoretically, Memristors, a concatenation of “memory resistors”, are a type of passive circuit elements that maintain a relationship between the time integrals of current and voltage across a two terminal element.
you can be friend with me on orkut
"mangalforyou@gmail.com" : i belive in sharing the knowledge so please send project reports ,seminar and ppt. to me .
(If visualization is slow, please try downloading the file.)
Part 2 of a tutorial given in the Brazilian Physical Society meeting, ENFMC. Abstract: Density-functional theory (DFT) was developed 50 years ago, connecting fundamental quantum methods from early days of quantum mechanics to our days of computer-powered science. Today DFT is the most widely used method in electronic structure calculations. It helps moving forward materials sciences from a single atom to nanoclusters and biomolecules, connecting solid-state, quantum chemistry, atomic and molecular physics, biophysics and beyond. In this tutorial, I will try to clarify this pathway under a historical view, presenting the DFT pillars and its building blocks, namely, the Hohenberg-Kohn theorem, the Kohn-Sham scheme, the local density approximation (LDA) and generalized gradient approximation (GGA). I would like to open the black box misconception of the method, and present a more pedagogical and solid perspective on DFT.
Theoretically, Memristors, a concatenation of “memory resistors”, are a type of passive circuit elements that maintain a relationship between the time integrals of current and voltage across a two terminal element.
This presentation contains information about some basic electrical parameters such as Voltage, Current, EMF, PD, Electric Power, Energy Ideal & Practical Sources, Types of Resistance, Heating Effect, Magnetic effect & Chemical effect of Electric Current etc.
Cable sizing to withstand short circuit currentLeonardo ENERGY
In a cable a short circuit causes very extreme stresses which are proportional to the square of the current:
• A temperature rise in the conducting components subjected to current flow such as conductor, screen, metal sheath, armour. Indirectly the temperature of adjoining insulation and protective covers also increases,
• electro-magnetic forces between the current-carrying components.
The temperature rise is important for its effect on ageing, heat pressure characteristics etc., and should be limited to a permissible short-circuit temperature. The thermo-mechanical effects of the current shall also be considered.
For a given short-circuit duty therefore the short-circuit capacity of a cable installation is to be investigated with respect to all these parameters. For multi-core cables in most instances the thermal effect - related to the magnitude of fault current and clearance time - is the critical parameter, since the cable will normally have enough mechanical strength. With single-core cables however, in addition, the mechanical effect - related to the magnitude of the peak short-circuit current - is of such significance that, next to the thermal, the mechanical with- stand of both cable and its supports is to be investigated.
Also accessories must be rated with respect to thermal and mechanical short-circuit stresses.
The short-circuit withstand of a cable system is not quantitatively defined with regard to permissible number of repeated short circuits, degree of deformation or destruction or impairment quality. It is expected, however, that a cable installation will remain safe in operation and that any deformation remains within tolerable limits even after several short circuits.
2. INTRODUCTION
• Memristor is a concatenation of “memory resistors”.
• Fourth passive circuit element.
• Maintain a relationship between the time integrals of current and voltage across a
two terminal element.
• Nonlinear resistor with memory.
MEMRISTOR SYMBOL
3. HISTORY
• Theory was developed in 1971 by Professor Leon Chua at University of
California, Berkeley.
• In 2008, a team at HP Labs under R.Stanley Williams claimed to have found
Chua's missing memristor based on an analysis of a thin film of titanium
dioxide.
• In March 2012, a team of researchers from HRL Laboratories and the
University of Michigan announced the first functioning memristor array built
on a CMOS chip.
4. MEMRISTOR
• Its resistance (dV/dI) depends on the charge that had flowed through the
circuit.
• When current flows in one direction the resistance increases, in contrast
when the current flows in opposite direction the resistance decreases.
• 2 terminal device relates magnetic flux and charge.
5. CONSTRUCTION
• Platinum acts as the electrodes.
• Two layers of Titanium dioxide is in between the electrode.
• One of which has a slight depletion of oxygen atoms.
6. • The oxygen vacancies acts as charge carriers.
• When positive voltage is applied , the holes are repelled .
• The length of depleted layer is increased, which increases the resistance.
• When negative voltage is applied , resistance decreases as length decreases.
7. PROPERTY
• Retain its resistance level even after the power supply is turned off or shut
down.
• Remembers or recalls the last resistance value that it had , before shut down.
• When the current is stopped the resistance retains the value that it had earlier.
• It means memristor “REMEMBERS” the current that had last flowed through it.
8. THEORY
• It defines relationship between magnetic flux linkage Φm(t) and the amount of
electric charge that has flowed, q(t)
f(Φm (t),q(t)) = 0
• The variable Φm ("magnetic flux linkage") is generalized from the circuit
characteristic of an inductor.
• It does not represent a magnetic field here.
• The symbol Φm may be regarded as the integral of voltage over time.
9. MEMRISTANCE
• In the relationship between Φm and q, the derivative of one with respect to the other
depends on the value of one or the other
• So each memristor is characterized by its memristance function describing the
charge-dependent rate of change of flux with charge.
M(q) =
dΦm
dq
Substituting the flux as the time integral of the voltage, and charge as the time integral
of current
M(q(t)) =
𝒅Φm/𝒅𝒕
𝒅𝒒/𝒅𝒕
=
V(t)
I(t)
10. APPLICATIONS
• Used in digital memory, logic circuits, biological and neuromorphic systems.
• Used in computer technology as well as digital memory
• Used in neural networks as well as analog electronics.
• These are applicable for analogic filter applications
• Remote sensing & Low-power applications.
• Used in Programmable Logic & Signal Processing.
• They have their own ability for storing analog
and digital data in an easy as well as power efficient
method
11. ADVANTAGES OF MEMRISTOR
• Has properties which can not be duplicated by the other circuit elements
(resistors, capacitors, and inductors)
• Capable of replacing both DRAM and hard drives
• Smaller than transistors while generating less heat
• Works better as it gets smaller which is the opposite of transistors
• Devices storing 100 gigabytes in a square centimeter have been created using
memristors.
• Requires less voltage (and thus less overall power required)
12. DISADVANTAGES OF MEMRISTOR
• Not currently commercially available
• Current versions only at 1/10th the speed of DRAM
• Could be learned but can also learn the wrong patterns in the beginning.
• Suspected by some that the performance and speed will never match DRAM
and transistors.
