Dielectrics in electric fields (1)
... constant (Ch 2) The band theory of solids is included because it is required to understand the energy levels of a dielectric, as in the conduction and formation of space charge (Ch 6-11) The energy ... review of the basics of dielectric and polymer science and builds upon it a comprehensive and very broad presentation of all aspects of modern dielectric theory and engineering, including the lastest ... important from the practical point of view The deleterious effects of high electric fields and/ or high temperatures occur in the form of conduction currents and the complex mechanism of conduction...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (2)
... distance of R from the midpoint of the axis of the dipole Let R + and R be the distance of the point from the positive and negative charge respectively (fig 1.1) Let R make an angle with the axis of ... Boston) 1.6 BAND THEORY OF SOLIDS A brief description of the band theory of solids is provided here For greater details standard text books may be consulted 1.6.1 ENERGY BANDS IN SOLIDS If there are ... conduction band or falling into the ground state Free electrons in the conduction band and free holes in the valence band can move under the influence of an electric field, though the mobility of the...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (3)
... of the cavity is zero and there are no short range interactions between the molecules in the cavity The internal field, Ej at the center of the cavity is the sum of the contributions due to The ... consider the first three of these in turn and the last mechanism will be treated in chapter 2.2 ELECTRONIC POLARIZATION The classical view of the structure of the atom is that the center of the atom ... lose some of the electronic charge in the process of formation of the molecule Consequently the center of gravity of the electronic charge is displaced with respect to the positive charges and a...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (4)
... 3.5 In the absence of an electric field the two sites are of equal energy with no difference between them and the particle may occupy any one of them Between the two sites, therefore, there is ... v-log u) the value of n may be determined With increasing value of n, the number of degrees of freedom for rotation of the molecules decreases Further decreasing the temperature of the material ... negative, that is, the center lies below the s' axis (fig 3.9) Figs 3.7 and 3.8 show the variation of s' and e" as a function of cox for several values of a respectively These are the plots of equations...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (5)
... through the structure of the material and therefore the relaxing dipole will affect the field seen by other dipoles of the cluster The neighboring dipoles may also relax exponentially affecting the ... Reserved E-Field The theory of Dissado and Hill is significant in that the application of their theory provides information on the structure of the material, though on a coarse scale The inter-cluster ... question and the result of screening is an effective reduction of the charge under consideration In a gas the charges are free and therefore the screening is complete, with the density of charge...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (6)
... mirror of the other The two forms are known as optical isomers If one form rotates the plane of plane-polarized light clockwise, the form is known as dextro-rotatory (prefixd) The other form will then ... molecular motion The shape of the a-relaxation of the amorphous polymer, while independent of temperature, is dependent upon the degree of crystallinity The width of the peak of the a-relaxation ... the effective xb as obtained by H-N fits The x-symbols stand for the ib obtained from KWW fits (ch 6) The dashed and the dash-dotted lines represent the Arrhenius and VF behavior of the (3- and...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (7)
... the basis of accumulation of positive charges within the polymer and close to the cathode The ions originate within the bulk of the material or are injected from the anode and drift towards the ... shows the function ^(t) as a function of (t/i) for a constant value of the parameters a, P, y = 0.5 For the purpose of comparison the exponential decay and the power law decay are also shown For ... Laplace transform for odd values of the exponent, y The absorption ratio, defined by the quantity shown on the ordinate (yaxis) is almost flat for small value of y = 0.1 For higher values the familiar...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (8)
... and therefore Nc and N0 are constants The rate of thermal excitation of electrons is, therefore, equal to the rate of capture of electrons by the donors The rate of thermal excitation of electrons ... imperfections and impurity atoms, the average velocity of electrons is zero and there is no current The mean kinetic energy of the electrons will, however, depend on the temperature of the lattice, and the ... (2) The current is a function of the number and drift velocity of electrons and not dependent on the position in the sample, z, measured from the cathode Denoting the number of electrons and the...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (9)
... reduced The number of ionizing collisions is also small because of the reduced number of neutral gas molecules for ionization On the other hand, at higher gas pressures, on the right hand side of the ... Other parameters that influence the formative times are the electrode geometry and the magnitude of the over-voltage Measured formative time lags can theoretically be interpreted in terms of the ... length, etc The origin of the streamer inception is the number of electrons at the head of the advancing primary avalanche When the number reaches a value in the range of 107 108 the electric...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (10)
... the end of the non-uniform region, then decreasing in the low field region because of the decrease in the total number of electrons in the low field region There is a shift between the peak of ... is whether the rate of change of the coefficients remains the same if p2/7V remains the same By considering the three sets of individual values of (32 and N such that their ratio remains the same, ... depending on the configuration of the electrode geometry, the characteristics of the insulating gas and the magnitude of the applied voltage which may or may not be time dependent The existence of a...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (11)
... nc is the number density of free carriers in the conduction band and frc is the recombination probability with the dimension of m3 s"1 The recombination probability is the product of the thermal ... velocity of free electrons in the conduction band, v, and the recombination cross section of the hole, arc 2) The electrons from the traps move to the conduction band due to thermal activation The ... from which the electron attempts to escape It acquires energy thermally and collides with the walls of the potential well, s is therefore a product of the number of attempts multiplied by the reflection...
Ngày tải lên: 21/03/2014, 12:08
dielectrics in electric fields (12)
... fields and a lattice polaron is formed The infrared 1 frequency domain is 10 -10 Hz and therefore the energy of the electron for the formation of a lattice polaron is lower, on the order of lattice ... view to understanding the variation of the electric field within the dielectric due to the applied field (2) To determine the depth of the charge layer and the distribution of the charge within ... function of the charge profile, of the position of the wave front in the sample, but also of the boundary conditions at the electrodes: Open circuit or short circuit conditions In the first case the...
Ngày tải lên: 21/03/2014, 12:08
... Streamlines of particles carried by the EOF were formed within the microchannels Particles entered from the left of the channels, traversed the whole structure, and then exited at the right outlet ... increases gradually The insulating concentrator was designed in this way to focus the electric field in the direction of the fluid flow (from the left to the right) The performance of the microfluidic ... of the channel Upon the application of the field, a non-uniform distribution is generated along the insulators, as indicated by the field lines Depending on the patterns of the insulators, the...
Ngày tải lên: 22/06/2014, 00:20
... fields The fields are usually the highest directly under the lines and fall rapidly with distance to the sides of the line Actual field strengths will, of course, vary depending on the height of the ... populations and observe statistical associations It cannot eliminate the many other possible factors that could determine the development of diseases and, therefore, cannot prove whether a particular ... effects of EMFs has been in progress for more than 30 years It is not reasonable to list or summarize the results of past and ongoing research in this document because of the great amount of information...
Ngày tải lên: 31/03/2014, 22:20
Cambridge.University.Press.A.Clinicians.Guide.to.Statistics.and.Epidemiology.in.Mental.Health.Measuring.Truth.and.Uncertainty.Jul.2009.pdf
... tolerate the unique gift, and danger, of the life of the academic: even when at home, ideas still roam around in one’s mind, and there is no end to the potential effort of reading and writing They ... patients or doctors; they are just there in the population and they can affect the results Two other types of confounding factors exist which are the result of the behavior of patients and doctors: confounding ... applied these concepts to medical illnesses and founded clinical epidemiology (The reader will see some of these names repeatedly in the rest of this book; the ideas of these thinkers form the basis...
Ngày tải lên: 24/09/2012, 09:06
Phân tích và đề xuất giải pháp nâng cao hiệu quả sản xuất kinh doanh của Công tyTNHH NISSEI ELECTRIC HÀ NỘI.docx
... kinh doanh ta phân loại theo cách khác theo tính tất yếu nhân tố, theo tính chất nhân tố, theo xu hướng tác động nhân tố nhân tố ảnh hưởng thuộc môi trường kinh doanh 1.3.1 Theo tính tất yếu nhân ... hiệu phân loại tiêu hiệu theo sau: Căn theo yêu cầu tổ chức xã hội tổ chức quản lý kinh tế cấp quản lý kinh tế quốc dân: Phân loại hiệu theo cấp hiệu ngành nghề, tiềm lực theo đơn vị kinh tế bao ... vào người kinh doanh Phân tích hiệu kinh doanh theo yếu tố chủ quan khách quan nhằm đánh giá nỗ lực thân tìm biện pháp tăng hiệu kinh doanh 1.3.2 Theo tính chất nhân tố Nhân tố số lượng: Phản...
Ngày tải lên: 28/09/2012, 16:47
Measuring Customer Satisfaction
... advertising should be made aware of the customer satisfaction findings Even if these staff and others anticipated the findings, confirmation of the success of their ideas and efforts could be rewarding ... required by the Paperwork Reduction Act and by the Rehabilitation Act to protect the privacy of customers served and to maintain the confidentiality of personal information collected by the program ... reevaluation of the original experiences resulting in a new understanding or appreciation of the original experiences and the context of those experiences Changes in the level of customer satisfaction, and...
Ngày tải lên: 23/10/2012, 13:33
Materials accounting in nissei electric hanoi company
... the cost of materials on hand at the beginning of the period To determine the cost of the ending materials, the units on hand at the end of the period must be counted and evaluated The cost of ... need for the business in order to maintain and sustain in the business for the longer period of time There are many advantages of the accounting software for the business First of all it helps the ... Under the LIFO method, the cost of last unit purchased is assumed to be the cost of first unit sold The cost of the most recent purchases is transferred to cost of materials used The cost of the...
Ngày tải lên: 06/11/2012, 10:26
Tài liệu mở rộng quản trị mạng IP Packet Header Fields
... means for the source of an internet datagram to supply routing information to be used by the gateways in forwarding the datagram to the destination, and to record the route information The option ... indicates the end of the option list This might not coincide with the end of the internet header according to the internet header length This is used at the end of all options, not the end of each ... with the option type code The second octet is the option length which includes the option type code and the length octet, the pointer octet, and length-3 octets of route data The third octet is the...
Ngày tải lên: 13/11/2012, 11:22