Achieving Color Uniformity Across Multi-Projector Displays Aditi Majumder Zhu He Herman Towles Greg Welch
Department of Computer Science,
University of North Carolina at Chapel Hill.
majumder,hez,towles,welch@https://www.doczj.com/doc/75927351.html,
Abstract
Large area tiled displays are gaining popularity for use in collabo-rative immersive virtual environments and scienti?c visualization. While recent work has addressed the issues of geometric regis-tration,rendering architectures,and human interfaces,there has been relatively little work on photometric calibration in general, and photometric non-uniformity in particular.For example,as a re-sult of differences in the photometric characteristics of projectors, the color and intensity of a large area display varies from place to place.Further,the imagery typically appears brighter at the regions of overlap between adjacent projectors.
In this paper we analyze and classify the causes of photometric non-uniformity in a tiled display.We then propose a methodology for determining corrections designed to achieve uniformity,that can correct for the photometric variations across a tiled projector dis-play in real time using per channel color look-up-tables(LUT). CR Categories: 1.3.5[Computer Graphics]:Projector Graphics and Optics
Keywords:Large Area Display,Tiled Displays,Projector Graph-ics,Color Calibration.
1Introduction
Large area displays provide new and stimulating areas of research and have the potential to change the way humans interact with their computing https://www.doczj.com/doc/75927351.html,rge,high-resolution,tiled displays that can extend to the walls,ceilings and?oors[4],have several advan-tages over traditional small computer screens.The high resolution and wide?eld-of-view(FOV)of such displays make them very use-ful for visualizing scienti?c data(PowerWall of University of Min-nesota,tiled projector displays of Sandia National Laboratories and Argonne National Laboratories)and complex open environments like battle?elds(Interactive DataWall of Rome Labs).They can be used as immersive surround displays(CA VE TM of University of Illi-nois at Chicago[2])to create a compelling sense of presence and immersion in a virtual environment.The life-size objects enable a natural interaction between multiple humans and virtual objects making such displays a wonderful tool for collaborative workspaces (Scalable Display Wall at Princeton[3],Interactive Mural at Stan-ford[1]and DataWall of MIT Media Lab).
There are several issues that are important when considering the development of large tiled display that is to operate as a single log-ical display.
1.Geometric Registration across Different Projectors:Re-cent years have seen a large amount of work done in this direction [4,5,6,7],which provided most of the solutions for geometric registration,even for arbitrarily shaped displays using arbitrarily positioned projectors.Thus,we can now envision building more ?exible tiled display systems,not being limited to planar displays or requiring rigid mechanical projector alignment.
2.Rendering Architecture and Algorithms:Interaction is likely to demand performance.While In?nity Wall or Power Wall are built using high-end multi-pipelined SGI graphics systems,more recent work has focussed on creating lower-cost,distributed PC rendering clusters.
3.Human Interface:The large tiled displays made up of multi-ple projectors,each of which may be driven by different graphics engines,should offer a human interface that hides this distributed nature of the system from a naive user and appears to be a single logical display.There has been some nice work in this direction at Stanford[1]and Princeton[3].
4.Photometric Uniformity:The projectors constituting the large area display,differ in their color/photometric characteristics.Some-times projectors are found to have color non-uniformities even within their own?eld of view.Further,the overlap region between projectors appear brighter than the non-overlapping areas.These result in photometric non-uniformity across a large tiled multi-projector display.
This photometric non-uniformity is very distracting even when there is a perfect geometric registration and can break the illusion of a single display device.Several perceptual and psychological stud-ies on human color perception and acuity support this observation [20].These studies show that humans are able to easily perceive a
difference in brightness and a difference in color resulting from a change as small as in the wavelength of light.
The comments in recent works on large tiled displays[8,9,1, 4,6],our interaction with others working in the same area,and our own experience has led us to believe that the problem of photo-metric non-uniformity of a multi-projector display is non-trivial and cannot be solved by some ad hoc means.We need a reliable method to calibrate the projectors photometrically which can be easily re-peated periodically as the projectors change photometrically.
In this paper,we endeavor to develop a rigorous characterization and analysis of the problem and?nd practical means of solving it in a structured fashion.We use a spectroradiometer to accurately characterize the photometric properties of various https://www.doczj.com/doc/75927351.html,-ing this information and fundamental photometric principles we de-velop methods to match the photometric characteristics of different projectors using per channel color LUTs.
1.1Main Contribution
The following are the main contributions of this work.
1.Analysis and Classi?cation:We analyze and classify the causes of photometric non-uniformity in a tiled display.
2.Photometric Calibration:We describe a methodology to cal-ibrate/match the photometric characteristics of different projectors in real-time using independent per channel color maps.For this,we use an optical sensing device as a feedback device.The results are repeatable and do not depend on human intervention.Further,our solution is based on basic principles of photometry/colorimetry and achieves the best matching that is possible using independent color LUTS.
3.Practical Demonstration:We also demonstrate a way to im-plement the corrections given the capabilities of present hardware to achieve the photometric uniformity in real-time.Our real-time implementation utilizes RGB color look-up-table(LUT),available in all image generators,to make independent channel corrections.
In Section2,we analyze the causes of photometric non-uniformity in multi-projector displays and identify parts of the problem that can be approached independently.In Section3,we present the theories and de?nitions that will be used in the rest of the paper.In Section4,we propose an algorithm to solve parts of the problem in real-time using a per channel color LUT.In Section5, we demonstrate the implementation of our algorithm by matching the color of different projectors such that geometrically registered images from two or more projectors appear look photometrically constant.Then we present the results in Section6and?nally con-clude by giving some insight on the work that still needs to be done in this direction.
2Causes of Photometric Non-Uniformity in Multi-Projector Displays
We categorize the problems of achieving photometric uniformity for a multi-projector display into four classes.Solving all of these problems will,in theory,achieve a photometrically uniform multi-projector display.
The problems can be classi?ed as:
I.Device Dependent
These problems are completely dependent on the projector characteristics.
(a)Photometric Variation Between Different Projectors
Two projectors have photometric variation due to differ-
ences in gamma,color gamut and the luminance range.
(b)Photometric Variation Within a Projector’s FOV
i.A very regular effect that we have observed is the
radial attenuation of brightness from the center to
the edges of the projector’s FOV.
ii.More irregular effects include the“blotchiness”of
different hues in different regions of the projec-
tor’s FOV.
II.Application Dependent
These problems are created by the way the projectors are used to form the multi-projector display.
(a)Photometric Variation Due to Overlapping Projectors
The region of the display surface where multiple pro-
jectors overlap will look brighter than the other regions
and,as a result,the image projected will have a‘seam’.
(b)Photometric Variation due to Non-Planar Non-
Lambertian Display Surface
i.The re?ection of light from one region of the dis-
play surface to another is called color bleeding.
One region of the display surface acts as a sec-
ondary light source for another region.
ii.In case of an arbitrarily curved non-diffuse sur-
face,the amount of light reaching a point on the
surface from the projector depends on the normal,
the coef?cient of re?ectance at that point and the
angle between the normal and the viewing direc-
tion.
The seams due to overlapping projectors in above,have been addressed previously[6,7]by employing a roll-off function such as a linear ramp or a cosine curve to smooth the intensity tran-sition between projectors.The problem of is complex and beyond the scope of this paper.
In this paper,we address the device dependent problems in above.Our goal is to change the input image to each projector in real-time in such a way that the large tiled display formed by the projection of these changed input images look photometrically seamless.To this end,we propose using the per channel color LUT available in all image generators and map the same input in different regions of the tiled display differently such that the projection of the mapped inputs are perceivably similar.
3Color Model
We present here a brief overview of the color model we use.More elaborate discussion can be found in[22,21,20].
The human visual spectrum includes lights of wavelength in the range of.There are three types of color:achro-matic(equal contribution from every wavelength)color which is perceived as gray,monochromatic(light of a single wavelength) which is impossible to generate physically and chromatic color(dif-ferent contributions from different wavelengths).Hue is the sensa-tion of color and differentiates a chromatic or monochromatic color from an achromatic color.A chromatic color with a broad spectrum is said to have low saturation,while a chromatic color with a nar-row spectrum has a higher saturation.A pure monochromatic color has saturation.
Several color speci?cation systems have been developed to describe the different properties of color.These systems do not depend on any particular device,and hence are referred to as device independent color spaces.
CIEXYZ Color Space:This color space was established in1931 by the CIE(Commission Internationale de Eclairage).In this color space,every color can be expressed as a linear combination of the CIE standard primaries,,and.
where is the color,and,and,,are the CIE tristimulus values.is called the luminance of.
The chromaticity values,and are de?ned from the tristim-ulus values as follows.
is called the chromaticity coordinates of a color and provides a measure of the chrominance(hue and saturation)of a color,while gives the sense of brightness.Thus uniquely de?nes any colored light in this CIEXYZ color space and is de?ned as the response of the colored light in this color space.
The cone shaped volume shown in Figure1contains the visible colors in the color space.Now,let us consider the set of
Figure1:The cone of visible colors in the CIE color
space
510
Figure2:CIE Chromaticity Diagram
planes,where is a constant.Two such planes are
shown by the shaded triangles in Figure1.Let us take two colors
and on the two different triangular planes but on the same straight
line starting from the origin.These two colors have the same hue
and saturation()but different luminance().
Figure2shows the result of plotting and for all visible colors.
This is called the CIE chromaticity diagram.The interior and the
boundary of the horse-shoe shaped region represent all the visible
chromaticity values.A standard white light is formally de?ned at where.The saturated monochromatic colors form the outer border of this region while the colors in the
interior of the horse-shoe are desaturated.A straight line joining and any point on the border,represents the locus of the same hue with different levels of saturation.This diagram factors out the luminance and shows only the chrominance on constant luminance plane.When two colors are added together,the new color lies on the straight line joining the two original colors in the chromaticity diagram.
Chromaticity diagram helps to visualize the color gamuts.All
the colors that can be reproduced by a device lies within the trian-
gle joining the three color primaries,and of a device in the
chromaticity diagram.Thus,chromaticity diagram helps us com-
pare the color primaries in different color devices,and needless to
say,none of them can reproduce all the visible colors.The triangle
in dotted lines in Figure2shows one such color gamut.If the chro-maticity coordinates of,and are,and respectively,then the chromaticity coordinates
of a color with respect to the chromaticity of,
and is
(1)
(2) where,.Distance Measures:The distance between two colors can be mea-sured using different distance metric starting from the simple Eu-clidian distance to more complex perception based distance metric. For our work we use a measure similar to the perception based metric derived by Katoh[10].Like,our distance metric is dependent on three difference terms–one luminance and two chro-maticity.For two colors,and,where the responses of and are and respectively,the distance is de?ned as follows.
(3) where is a normalization factor,
with and,as de?ned in. For our purpose,we de?ne as the maximum luminance that can be generated by a projector.In practice,we consider the two colors matched if where is a small positive quantity.
4Algorithm Overview
We present an algorithm which needs minimal human intervention. Our approach is to measure and match colors from different projec-tors against a standard,device independent color space.We use a Photo Research PR-705spectroradiometer as our reference sensor.
4.1Problem De?nition
Let us assume that we are trying to achieve photometric uniformity across an projector display system with projectors
with resolution of.Based on the analysis in Section3, we can assume that the color projected by projector for input
at pixel,is a function of, ,and,.The condition for photometric uniformity of projectors is,for any input,the colors perceived at every pixel of every projector are equivalent.More formally,for any two pixel and of any two projector and respectively,
(4) Of course in practice,Equation4is seldom true because of the de-vice dependent problems outlined in Section2.
4.2Our Approach-Color Mapping
Our goal is to develop a color map so that the same input in all projector pixels produce perceptually identical input color.Now,let be the set of all inputs.A color map is a function that maps each input color to a new input color.In order to achieve photometric uniformity,we need to generate color maps and for every pixel and of projector and respectively,such that,
(5)
If Equation5is satis?ed,we say that the color maps and have equivalent response and denoted it by
(6)
Thus for the same input,if we use the input speci?ed by the color map at that pixel of that projector,then we can satisfy Equa-tion4,and will have photometric uniformity across all projectors.
Given a-bit color representation,the task is to map each of the color inputs to a new input.Further,if we have to take care of the photometric variations within projector’s own FOV,a large
Figure3:Left:Luminance Response before and after Non-Linearity Correction;Middle:Chromaticity is near constant with the increase in input values;Right:Chromaticity is near constant with the increase in input values
color map could conceivably be generated for every pixel.
Clearly,mapping every possible input for every pixel location is
impractical today.
However,there are two ways to reduce the complexity of the
problem.We can subsample in the spatial domain and use a smaller
number of color maps(not for every pixel)to equalize the differ-
ence in?eld uniformity of each projector,and also subsample the
input domain of all possible colors.
4.3Sub-sampling in the Spatial Domain
Instead of generating a color map for each pixel of each
projector,we propose the following simpli?cation.Let us de?ne
a proper subset of pixels
de?ned by sub-sampling the projector frame-buffer based
on the pattern of color variation across the projector.For every
pixel,the color map is a weighted average of the color maps
of its nearest neighbors in.We believe that the biggest problem
here is to decide on the number of samples required to adequately
correct the color variations across the projector FOV.
4.4Sub-sampling in the Input Domain
The idea of sub-sampling the input space and generating the inter-
mediate colors using interpolation is not new.[12,11,15]propose
different kinds of sampling and interpolation techniques for doing
this.However,none of these proposed techniques are computation-
ally intensive and complex and cannot be implemented in real-time.
The applications of large tiled displays(presented in Section1)de-
mands a real-time solution for the color-matching problem.
If we were doing a correction for a monochrome projector,we
would generate a mapping on a domain of inputs.Since color
consists of three independent channels,,and,each of which
is functionally equivalent to a single monochrome channel,an im-
mediate possibility for subsampling the input domain is to de?ne
a mapping for each of these channels independently.This reduces
the input domain space cardinality from to.
However,we need to design this mapping in such a way,that the
colors projected by superposition of the independent color maps
for each channel,match.Mathematically,instead of?nding two
complete color maps as in Equation6,we want to subsample the
input domain by approximating and by a set of per channel
color maps and.Thus we need to de?ne
and in such a way that,
(7)
In the next section,we describe our techniques for generating such
per channel color
maps.
Input
Input
Figure4:Left:Non-Linearity Correction;Right:Luminance Cor-
rection
4.5Per Channel Color Map Generation
We describe the process of generating the mapping function for one
channel.This method is repeated for the three channels-red,green
and blue.The method is comprised of three steps:Non-Linearity
Correction,Luminance Matching and Chrominance Matching.
Each of these steps produces an intermediate mapping function.
The?nal mapping function for each channel is a simple concate-
nation of the maps generated by these three steps.
4.5.1Non-Linearity Correction
The input-output luminance response of each channel of a pro-
jector is found to be non-linear(Figure3).While conventional
CRT devices also exhibit non-linearities that are typically addressed
by gamma correction,we allow for a more general class of non-
linearities and correct for them.
Let us denote the input to a particular channel as.Let us de-
note the luminance corresponding to and the
projected by a projector as and respectively.The non-
linearity correction method generates a mapping function to lin-
earize the input-output response for the projector as shown in Fig-
ure4.is the piecewise linear curve generated by mea-
suring the luminance response of projector.To achieve a linear
response,every input is mapped to an input such
that.Thus the response we get after the non-
linearity correction is
.
4.5.2Luminance Matching
We choose a luminance which is the maximum of all’s
(brightest black)and a luminance which is the minimum of all
’s(dimmest white).Figure4depicts the method to generate a lu-
minance map.The goal is to compress the luminance range of each
projector within and(within the brightest black and dimmest
Figure5:Luminance Response for for the Red Channel of two Projectors.Left:Before Luminance Matching:Right:After Luminance Matching.The response of the other channels are similar.
white)to achieve a response.For this
we generate a luminance map where
and.Thus,the response we get after
the luminance correction is
Thus after non-linearity and luminance matching,every input is
mapped to.With this transformation,each channel
of all projectors have exactly the same channel response with
the same highest and lowest luminance levels.In other words,the
luminance of the response of the same input from two different
projectors and differ by.Now,since the luminance of the
response for any input is a summation of the
luminances of the responses of each of,and,the luminance
of the same input from two different projectors and can differ
by a maximum of.Thus,after the luminance matching step we
have minimized the luminance term in the distance between the
responses of the same input from different projectors which now
depends entirely on the chromaticity differences.
Figure3shows a typical chromaticity response for our projec-
tors1.Here we observe that for each channel,the
chromaticity coordinates of the CIE response of re-
main relatively constant over a large input range,.
We also observe that this constant value is nearly equivalent for dif-
ferent kinds of projectors.Table1shows the average chromaticity
coordinates of the different brands of projectors and the maximum
distances between the same channel of two different brand projec-
tors.
In this scenario,the distance between two colors from differ-
ent projectors,which now depends only on the chrominance terms,
becomes a constant and,we cannot minimize the distance any fur-
ther by just using independent per channel color maps.Since the
constant chromaticity value for the response of each channel of dif-
ferent projectors in the input range of are close
to each other,the luminance matching step will attain a good color
match.
But,this characteristic is not true for the whole input range and
the chromaticities of the different projectors differ signi?cantly in
the input range.Thus,there is a possibility of im-
proving the overall distance differences in this input range by relax-
ing the luminance match to reduce the differences in chrominance.
and thus achieve a perceptually better color match.
1Four Sharp XG-E3000U,two NEC MT-1035,one nView D700Z and a
Sony VPL-X600U
Projector Brand Red Green Blue
x y x y x y
Sharp0.620.320.330.620.140.07
NEC0.550.310.350.570.150.09
nView0.540.340.280.580.160.07
Max Distance0.0850.0860.028
Table1:Chromaticity Coordinates of the primaries of different
brands of projectors
4.5.3Chrominance Matching
To generate a chromaticity map for each channel,we begin by iden-
tifying one of the projectors arbitrarily as the reference projector
.The chromaticity map of the reference projector is an identity
mapping function.The chromaticity map for all other projectors is
generated as follows.
for every input in projector
?nd the response of;
endfor
for every input in projector
?nd such that the distance
between and is minimum
Map input of projector to
endfor
We should search for within the entire input space of
so that we get the best match,but we have empirically found that
is a good estimate to reduce the search space.
Now we show that after the chrominance matching step,for
any input,the condition given by Equation7
is satis?ed.Let the maximum of all(calculated during the
chrominance matching step)be.Let us consider two projec-
tors and and their responses for an input be
and respectively.
Let and.The
responses of and are similarly de?ned.
By the design of the chromaticity map,
We have to prove that is bounded.The above
equations and Equation3imply that the following
Figure6:Chromaticity Response for the Two Projectors for the green channel.Left:Before Chrominance Matching;Right:After Chromi-nance Matching.The response of the other channels are similar
holds
Now,using Equations1and2
Thus is a convex combination of,.
Further,https://www.doczj.com/doc/75927351.html,ing these results we can
show that
Similarly,
Also,the luminance difference
Hence
4.6Hardware Solutions
The solution presented in section4.5can be implemented in real-
time using conventional hardware.Most image generators include
a hardware look-up table(LUT)per channel,which is normally
used for CRT gamma correction,as the last functional block before
digital-to-analog conversion.We propose to use this same LUT to
implement our color map.Given access to this LUT,we can re-
place the standard gamma correction with the color map detailed
above,thereby achieving color matching of the projectors.Ideally
we would like more than one color map to represent the spatial do-
main of each projector,as discussed in Section4.3.But in most
graphics hardware we have access to only8-bit image channels
and LUTs and cannot afford to sacri?ce color intensity resolution.
However.in other high-end systems with image and LUT width of
10/12bits,it will be possible to allocate2/4bits to access different
color maps associated with4/16different spatial region of the pro-
jector image.Our results in the color plate show that implementing
the solution in Section4.5even for one spatial sample per projector
can signi?cantly improve color matching.
4.7Optical Sensing Device
In selecting the optical sensor used in our investigation,we con-
sidered using a high quality color camera,but chose to utilize a
precision spectroradiometer.By selecting the spectroradiometer,
we could work in a laboratory-calibrated device-independent color
space and avoid converting the measurements from the device-
dependent color space of the camera.We also avoid the possibility
that the camera color gamut might not completely encompass the
projector color gamuts.However,it should be noted that a part of
our algorithm is directed towards making it very easy to use a cam-
era as an optical sensing device.We have designed our algorithm to
do the luminance and chrominance matching separately,instead of
doing it in one single step using some popular distance metric[10].
When a camera is used instead of a spectroradiometer,it does not
limit the measurement of luminance.Thus the luminance matching
step of our algorithm will yield similar results,when implemented
using a linear response color camera.
With regard to using a camera for the chrominance matching,
methods exist for converting to device independent space from the
camera’s color space[16]and for gamut mapping2[10,17,18,19].
Since gamut mapping is a many-to-one mapping,one will not be
able to generate the‘gold standard’results produced by the spec-
troradiometer in the chrominance matching step,unless the color
gamuts of all the projectors happen to be within the camera color
gamut.However,assuming that the camera has a good gamut map-
ping algorithm[10,14],the results of the chrominance matching
step will be comparable to that achieved by the spectroradiometer.
5Implementation
We have implemented our solution for display of up to four pro-
jectors,both abutting and overlapping,on a planar surface,with
one color map per channel of each projector generated at only one
sample pixel in the projector’s FOV.Thus our solution assumes uni-
form color across the FOV of each individual projector(Case I.a in
section2).
We have used this method to calibrate and compare several dif-
ferent LCD and Texas Instruments DLP TM based projector combi-
2Gamut Mapping is a method to map a out-of-gamut color to a color in
the device gamut that has the least distance to it.
nations.We applied the methods to three combinations of abutted projector pairs:Two Sharp XG-E3000U,a nView D700Z and a Sony VPL-X600U,and a nView D700Z and a Sharp XG-E3000U. Lastly,we used four NEC MT-1035projectors,overlapping each other,in three different con?gurations to form large tiled displays. To correct for the photometric variation in the overlapping region, we employ a blending function as described in[6,7].
We used a highly diffuse,close to Lambertian material for our projector screen.We kept the settings,location and orientation of a projector the same for all the experiments during the process of matching its color,so that the results have a consistent inter-pretation and are repeatable.We used a Photo Research PR-705 spectroradiometer and measured the output response of each projector for equally spaced input values between and. To demonstrate our algorithm,we use OpenGL TM rendering,where the user can load and access a color look up table.We achieved similar results for all pairs of projectors and hence present the results for the pair of Sharp projectors only.
Veri?cation of Non-Linearity Correction:Figure3shows the input-output response before the non-linearity correction step.The straight line in Figure3shows the response of all the channels after this step.
Veri?cation of Luminance Matching:In Figure5we show the luminance response curve of the red channel of two different projectors,before and after the luminance matching step.The curves are almost coincident after the luminance matching.In Figure7we present the luminance response for grays to show that the matching works for achromatic colors even if we have done the matching for each of the channels separately.
Veri?cation of Chrominance Matching:In Figure7,we show the chromaticity response of the grays after the chrominance match-ing step.The response is very close to–which shows that we have maintained the balance of the contribution of red, green and blue,while applying chrominance matching separately to each channel.In Figure6,we show the chromaticity response of the red channel of two different projectors before and after the chrominance matching step.This shows that we have improved the chrominance matching while preserving the luminance match-ing.We also do an input-output response analysis for the projectors after the chrominance matching step and?nd the chromaticity co-ordinates of each channel are still near constant.
6Results
We present the results of our algorithm in the color plates and the Quicktime TM movie in the electronic version of the proceedings.We show our results using two sets of horizontal color bars.One of these two sets of colors are chosen to have the input values in the region where the constant chromaticity characteristic is not satis-?ed.Our algorithm appears to achieve perceptually acceptable re-sults in that region also.We believe that for some colors in our color plate images,the process of going from a digital camera to a color printer may have exaggerated chromaticity mismatches compared to the actual observed results.
In the color plate,we show each of the correction steps for a nView-Sony projector pair.We show the?nal results for a nView-Sharp pair.In these two cases,we deliberately adjusted the image controls of our projectors to make them differ greatly in luminance and color to demonstrate the matching capabilities of our algorithm. But,in such cases,the brighter projector loses much of its dynamic range after calibration.Hence,we ran our color correction meth-ods on a pair of Sharp projectors after we adjusted the brightness and the contrast control of the projectors to match the black and
Input(r,g,b)color distances
nView-Sony pair Sharp Pair
Before After Before After
(1.0,0.0,0.0)23.03 1.07 2.15 1.53
(0.0,1.0,0.0)221.36 1.4631.92 1.18
(0.0,0.0,1.0)16.830.95 4.860.09
(0.0,1.0,1.0)239.31 2.3237.600.70
(1.0,0.0,1.0)38.75 1.99 3.78 1.79
(1.0,1.0,0.0)244.33 2.8630.90 1.70
(0.5,0.0,0.0)7.780.158.120.15
(0.0,0.5,0.0)60.46 3.7110.920.70
(0.0,0.0,0.5) 4.860.190.510.16
(0.0,0.5,0.5)63.92 3.7212.750.53
(0.5,0.0,0.5)11.980.327.800.19
(0.5,0.5,0.0)67.07 3.62 4.63 1.05
(0.13,0.04,0.22) 2.550.08 2.07 3.93
(0.26,0.09,0.30) 5.880.48 4.34 4.75
(0.30,0.98,0.04)221.71 1.1729.13 1.20
(0.43,0.87,0.11)197.22 3.6026.100.07
(1.0,1.0,1.0)237.3724.6536.10 2.40
(0.0,0.0,0.0)0.920.170.900.37
Mean92.52 2.928.59 1.23
Std.Dev.100.30 5.5912.00 1.35 Table2:Color differences before and after calibration white levels.We used our spectroradiometer as the feedback de-vice while doing this adjustment.Thus we preserved the dynamic range of the projectors as much as possible after calibration.We also show the results of our color calibration on large tiled displays made up of four overlapping projectors.In the electronic version of the proceedings,we show the real-time performance of our al-gorithm by rendering a dynamic scene using color look-up-tables. However,the digital images of the dynamic scene in the color plates illustrates the color matching better.
To quantify the amount of correction from the nView-Sony and the pair of Sharp projectors before and after photometric calibration,we show the distance between two similar in-puts in a perceptually uniform CIE LUV[20]color space in Table2.
Observations:As has been observed by many visual perceptual studies before,we also?nd that luminance is more important for perception than chrominance.Further,as expected by the design of our algorithm,the correction after the chrominance matching step is perceivable only for the color which have one of the inputs in the https://www.doczj.com/doc/75927351.html,stly,when a color from one projector is not within the color gamut of another,it is impossible to match the color exactly.In such cases,if we have overlapping projectors with some blending function to blend in the overlapping region, instead of the abutting ones,then the smooth transition makes the mismatch perceptually less noticeable.
7Conclusions
Photometric uniformity across different projectors of a multi-projector display is a non-trivial problem,and we have made an attempt to solve it using the basic principles of photometry.We have proposed a repeatable method to match the colors of a system of arbitrarily different projectors using an accurate optical sensing device like a spectroradiometer.Further,we have demonstrated a practical implementation of the solution to show how it can be used to apply the photometric correction in real-time.
In the future we would like to utilize multiple color maps per projector to compensate for display?eld non-uniformity within a single projector.We are in the process of mounting the spectrora-diometer to a pan-tilt unit to automate the measurement process of
Figure7:Left:Luminance Response for Grays after Luminance matching;Middle:Luminance Response of red and green channels after Chrominance Matching.The response for blue is similar.Right:Chrominance response of gray after chrominance matching.
the different spatial points in a projector’s FOV.We can use our high
end SGI with12-bit LUTs to implement spatially indexed color
map corrections.We wish to investigate the use of low-cost color
cameras to replace the spectroradimeter.Further,we would like to
explore projector image controls for improved luminance and color
balance before applying our color map method,thereby reducing
the loss of dynamic https://www.doczj.com/doc/75927351.html,stly,though we achieved results that
were perceivably acceptable(as shown in Table5),we would like
rede?ne the same algorithm in a perceptually uniform color space.
In conclusion,the paradigm we have presented for color match-
ing light projectors can be applied today to improve the presentation
quality of tiled displays.Further,it establishes a foundation that
will enable us and other researchers to look for further improved,
application-oriented solutions to this dif?cult problem.
Acknowledgements
This work was supported by DOE ASCI Views program;the
“National Tele-Immersion Initiative(NTII)”sponsored by Ad-
vanced Network and Services,Inc.and the NSF Cooperative
Agreement no.ASC-8920219:“Science and Technology Cen-
ter for Computer Graphics and Scienti?c Visualization”;We also
thank the Intel Corporation for their generous equipment donation
as a part of Technology for Education2000.
References
[1]G.Humphreys and P.Hanrahan,“A Distributed Graphics System for Large Tiled
Displays”,Proceedings of IEEE Visualization’99.
[2]Cruz-Neira,Carolina,D.J.Sandin and T.A.Defanti“Surround-Screen Projection-
Based Virtual Reality:The Design and Implementation of the CA VE”,ACM
Computer Graphics(Proceedings of Siggraph’93).
[3]R.Samanta,J.Zheng,T.Funkhouse,K.Li and J.P.Singh,“Load Balanc-
ing for Multi-Projector Rendering Systems”,SIGGRAPH/Eurographics
Workshop on Graphics Hardware,August1999(See also
https://www.doczj.com/doc/75927351.html,/omnimedia/index.html,cited October20,1999).
[4]R.Raskar,G.Welch,M.Cutts,https://www.doczj.com/doc/75927351.html,ke,L.Stesin,H.Fuchs,“The Of?ce of the Fu-
ture:A Uni?ed Approach to Image Based Modeling and Spatially Immersive
Displays”,ACM Computer Graphics(Proceedings of Siggraph’98),pp.179–
188.
[5]R.Raskar,M.Cutts,G.Wech,W.Stuerzlinger,“Ef?cient Image Generation for
Multiprojector Multisurface Displays”,9th Eurographics Rendering Workshop,
’98.
[6]R.Raskar,cG.Wech,H.Fuchs,“Seamless Projection Overlaps Using Image Warp-
ing and Intensity Blending”,Fourth International Conference on Virtual Systems
and Multimedia,November’98.
[7]R.Raskar,M.S.Brown,R.Yang,W.Chen,G.Welch,H.Towles,B.Seales,H.Fuchs.
1999.“Multi-Projector Displays Using Camera-Based Registration,”Proceedings
of IEEE Visualization99,San Fransisco,CA,October24-29,1999.
[8]M.Herald,I.R.Judson,R.L.Stevens,“Introduction to Building Projector-Based
Tiled Display Systems”,IEEE Computer Graphics and Applications,July/August
2000,pp22-28.
[9] D.R.Schikore,R.A.Fischer,R.Frank,R.Gaunt,J.Hobson,B.Whitlock,“High Res-
olution Multiprojector Display Walls”,IEEE Computer Graphics and Applica-
tions,July/August2000,pp38-44.
[10]N.Katoh,S.Ohno,“Three-dimensional Gamut Mapping Using Various Color
Difference Formulae and Color Spaces”,Journal of Electronic Imaging8(4),Oc-
tober1999,pp365-379.
[11]J.M.Kasson,S.I.Nin,W.Plouffe,J.L.Hafner,“Performing Color Space Conver-
sions with Three-dimensional Linear Interpolation”,Journal of Electronic Imag-
ing4(3),July1995,pp226-250.
[12]P.C.Hung,“Colorimetric Calibration in Electronic Imaging Devices Using a
Look-Up-Table Model and Interpolations”,Journal of Electronic Imaging2(1),
October1993,pp53-61.
[13]R.Balasubramanian,R.de Queiroz,Z.Fan,“Multiresolution Color Correction”,
SPIE Proceedings3300,Color Imaging:Device Independent Color,Color Hard-
copy and Graphics Arts III,1998,pp163-172.
[14]K.E.Spaulding,R.N.Ellson,J.R.Sullivan,“UltraColor:A New Gamut Mapping
Strategy”,SPIE Proceedings2414,Device Independent Color Imaging II,1998,
pp61-68.
[15]J.M.Kasson,W.Plouffe,S.I.Nin,“A Tetrahedral Interpolation Technique for
Color Space Conversion”,SPIE Proceedings1909,Device Independent Color
Imaging and Imaging Systems Intergration,January1993,pp127-138.
[16] D.Brydges,F.Deppner,H.Kunzil,K.Heuberger,R.D.Hersch,“Application of a
3-CCD color Camera for Colorimetric and Densitometric Measurements”,SPIE
Proceedings3300,Color Imaging:Device Independent Color,Color Hardcopy
and Graphics Arts III,1998,pp292-301.
[17]N.Tsumura et.al.,“Color Gamut Mapping based on Mahalanobis Distance for
Color Reproduction of Electronic Endoscope Image under Different Illuminant”,
Proceeding of Imaging Science and Technology/SID’s Color Imaging Conference,
1997,pp158-162.
[18]N.Katoh,M.Ito,“Gamut Mapping for Computer Generated Images”,Proceeding
of Imaging Science and Technology/SID’s Color Imaging Conference,1996,pp
126-129.
[19]S.Nakauchi et.al.,“Color Gamut Mapping by Optimizing Perceptual Image
Quality”,Proceeding of Imaging Science and Technology/SID’s Color Imaging
Conference,1996,pp63-67.
[20]Edited by H.John Durrett,Interactive Systems Laboratory,San Marcos,Texas,
“Color and the Computer”,Academic Press,INC,1986
[21] E.J.Giorgianni,T.E.Madden,“Digital Color Management Encoding Solutions”,
Addison-Wesley,1998
[22] A.Majumder,“Color Perception and Measurement”,University of North Car-
olina at Chapel Hill,Department of Computer Science,Technical Report TR99-
033.
商务公文写作目录 一、商务公文的基本知识 二、应把握的事项与原则 三、常用商务公文写作要点 四、常见错误与问题
一、商务公文的基本知识 1、商务公文的概念与意义 商务公文是商业事务中的公务文书，是企业在生产经营管理活动中产生的，按照严格的、既定的生效程序和规范的格式而制定的具有传递信息和记录作用的载体。规范严谨的商务文书，不仅是贯彻企业执行力的重要保障，而且已经成为现代企业管理的基础中不可或缺的内容。商务公文的水平也是反映企业形象的一个窗口，商务公文的写作能力常成为评价员工职业素质的重要尺度之一。 2、商务公文分类：（1）根据形成和作用的商务活动领域，可分为通用公文和专用公文两类（2）根据内容涉及秘密的程度，可分为对外公开、限国内公开、内部使用、秘密、机密、绝密六类（3）根据行文方向，可分为上行文、下行文、平行文三类（4）根据内容的性质，可分为规范性、指导性、公布性、陈述呈请性、商洽性、证明性公文（5）根据处理时限的要求，可分为平件、急件、特急件三类（6）根据来源，在一个部门内部可分为收文、发文两类。 3、常用商务公文： （1）公务信息：包括通知、通报、通告、会议纪要、会议记录等 （2）上下沟通：包括请示、报告、公函、批复、意见等 （3）建规立矩：包括企业各类管理规章制度、决定、命令、任命等； （4）包容大事小情：包括简报、调查报告、计划、总结、述职报告等； （5）对外宣传：礼仪类应用文、领导演讲稿、邀请函等； （6）财经类：经济合同、委托授权书等； （7）其他：电子邮件、便条、单据类（借条、欠条、领条、收条）等。 考虑到在座的主要岗位，本次讲座涉及请示、报告、函、计划、总结、规章制度的写作，重点谈述职报告的写作。 4、商务公文的特点： （1）制作者是商务组织。（2）具有特定效力，用于处理商务。 （3）具有规范的结构和格式，而不像私人文件靠“约定俗成”的格式。商务公文区别于其它文章的主要特点是具有法定效力与规范格式的文件。 5、商务公文的四个构成要素： （1）意图：主观上要达到的目标 (2）结构：有效划分层次和段落，巧设过渡和照应 (3）材料：组织材料要注意多、细、精、严 (4) 正确使用专业术语、熟语、流行语等词语，适当运用模糊语言、模态词语与古词语。 6、基本文体与结构 商务文体区别于其他文体的特殊属性主要有直接应用性、全面真实性、结构格式的规范性。其特征表现为：被强制性规定采用白话文形式，兼用议论、说明、叙述三种基本表达方法。商务公文的基本组成部分有：标题、正文、作者、日期、印章或签署、主题词。其它组成部分有文头、发文字号、签发人、保密等级、紧急程度、主送机关、附件及其标记、抄送机关、注释、印发说明等。印章或签署均为证实公文作者合法性、真实性及公文效力的标志。 7、稿本 （1）草稿。常有“讨论稿”“征求意见稿”“送审稿”“草稿”“初稿”“二稿”“三稿”等标记。（2）定稿。是制作公文正本的标准依据。有法定的生效标志（签发等）。（3）正本。格式正规并有印章或签署等表明真实性、权威性、有效性。（4）试行本。在试验期间具有正式公文的法定效力。（5）暂行本。在规定
第一部分车轮的基本知识 人们习惯所说的“轮毂”是指汽车中的一个部件，其英文是“WHEEL”，其实他的准确中文术语应是“车轮”。 车轮——作为汽车整车行驶部分的主要承载件，是影响整车性能最重要的安全部件之一。它不仅要承受静态时车辆本身垂直方向的载荷(包括自重载荷以及人和货物的载重量)，更需要经受车辆行驶中来自各个方向因起动、制动、转弯、风阻、石块冲击、路面凹凸不平等各种动态载荷所产生的不规则应力的考验。车轮也是影响整车外观造型的装饰件，可以说是衡量整车质量和档次的最主要象征之一。那么，一款安全、优质、美观与实用性并重的车轮是如何生产出来的呢？ 一、车轮的基本结构
1、轮辋：与轮胎装配配合，支撑轮胎的车轮部分。 2、轮辐：与车轴车轮实施安装连接，支撑轮辋的车轮部分。 3、偏距：轮辋中心面到轮辐安装面间的距离。有正偏距、零偏距、负偏距之分。 4、轮缘：保持并支撑轮胎方向的轮辋部分。 5、胎圈座：与轮胎的胎圈接触，支撑维持轮胎半径方向的轮辋部分。 6、槽底：为方便轮胎装拆，在轮辋上留有一定深度和宽度的凹坑。 7、气门孔：安装轮胎气门嘴的孔。 二、车轮的生产流程及相关检验标准 1、熔炼（Melt） 将原材料铝锭（A356）经过熔炼设备，合格的铝水必须经过抽样成型后放到光谱仪（Spectrumeter）里检查成分，只有成分符合标准才允许转下一工序。 图（2） 2、铸造（Casting） 采取低压铸造方式，铝水在下，模具在上，用底压方式使铝水往上升，透过浇口铸造成形。 X光检测（探伤检查）：检测铸件的缩松、气泡、渣滓等情况。
（3） 3、热处理 热处理的目的是提高车轮的机械性能，即提高车轮的抗拉强度、延伸率和硬度。 图（4） 4、机加工 用数控车床对铸件毛坯进行机械加工，包括对轮辋、安装面、中心孔的加工；用加工中心加工螺栓孔、气门孔及装饰孔等。 径向/横向跳动量测试：目的是检验车轮机加工的精确性，用以保证汽车行驶的安全
关于会议纪要的规范格式和写作要求 一、会议纪要的概念 会议纪要是一种记载和传达会议基本情况或主要精神、议定事项等内容的规定性公文。是在会议记录的基础上，对会议的主要内容及议定的事项，经过摘要整理的、需要贯彻执行或公布于报刊的具有纪实性和指导性的文件。 会议纪要根据适用范围、内容和作用，分为三种类型： 1、办公会议纪要(也指日常行政工作类会议纪要)，主要用于单位开会讨论研究问题，商定决议事项，安排布置工作，为开展工作提供指导和依据。如，xx学校工作会议纪要、部长办公会议纪要、市委常委会议纪要。 2、专项会议纪要(也指协商交流性会议纪要)，主要用于各类交流会、研讨会、座谈会等会议纪要，目的是听取情况、传递信息、研讨问题、启发工作等。如，xx县脱贫致富工作座谈会议纪要。 3、代表会议纪要(也指程序类会议纪要)。它侧重于记录会议议程和通过的决议，以及今后工作的建议。如《××省第一次盲人聋哑人代表会议纪要》、《xx市第x次代表大会会议纪要》。 另外，还有工作汇报、交流会，部门之间的联席会等方面的纪要，但基本上都系日常工作类的会议纪要。 二、会议纪要的格式 会议纪要通常由标题、正文、结尾三部分构成。
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titlesec&titletoc中文文档 张海军编译 makeday1984@https://www.doczj.com/doc/75927351.html, 2009年10月 目录 1简介,1 2titlesec基本功能,2 2.1.格式,2.—2.2.间隔, 3.—2.3.工具,3. 3titlesec用法进阶,3 3.1.标题格式,3.—3.2.标题间距, 4.—3.3.与间隔相关的工具, 5.—3.4.标题 填充,5.—3.5.页面类型,6.—3.6.断行,6. 4titletoc部分,6 4.1.titletoc快速上手,6. 1简介 The titlesec and titletoc宏包是用来改变L A T E X中默认标题和目录样式的，可以提供当前L A T E X中没有的功能。Piet van Oostrum写的fancyhdr宏包、Rowland McDonnell的sectsty宏包以及Peter Wilson的tocloft宏包用法更容易些；如果希望用法简单的朋友，可以考虑使用它们。 要想正确使用titlesec宏包，首先要明白L A T E X中标题的构成，一个完整的标题是由标签+间隔+标题内容构成的。比如： 1.这是一个标题，此标题中 1.就是这个标题的标签，这是一个标签是此标题的内容，它们之间的间距就是间隔了。 1
2titlesec基本功能 改变标题样式最容易的方法就是用几向个命令和一系列选项。如果你感觉用这种方法已经能满足你的需求，就不要读除本节之外的其它章节了1。 2.1格式 格式里用三组选项来控制字体的簇、大小以及对齐方法。没有必要设置每一个选项，因为有些选项已经有默认值了。 rm s f t t md b f up i t s l s c 用来控制字体的族和形状2，默认是bf,详情见表1。 项目意义备注（相当于） rm roman字体\textrm{...} sf sans serif字体\textsf{...} tt typewriter字体\texttt{...} md mdseries(中等粗体)\textmd{...} bf bfseries(粗体)\textbf{...} up直立字体\textup{...} it italic字体\textit{...} sl slanted字体\textsl{...} sc小号大写字母\textsc{...} 表1:字体族、形状选项 bf和md属于控制字体形状，其余均是切换字体族的。 b i g medium s m a l l t i n y（大、中、小、很小） 用来标题字体的大小，默认是big。 1这句话是宏包作者说的，不过我感觉大多情况下，是不能满足需要的，特别是中文排版，英文 可能会好些！ 2L A T E X中的字体有5种属性：编码、族、形状、系列和尺寸。 2
轮胎规格参数解释 胎规格，是轮胎几何参数与物理性能的标志数据。形象的说，就是车子所穿的四只鞋子的大小，鞋底的设计如何，是适合慢跑还是快跑。不同规格的轮胎对于整车的性能表现以及舒适性都会产生影响，下面我们一起看下。 轮胎规格表示含义 国际标准的轮胎规格，一般由六部分组成，“轮胎宽度（mm）+轮胎断面的扁平比（%）+轮胎类型代号+轮辋直径（英寸）+负荷指数+许用车速代号”。轮胎宽度、轮辋直径及扁平比如上图所示，其中扁平比为胎厚与胎宽的百分比。
轮胎宽度，是影响整车油耗表现的一个因素。轮胎的越宽，与地的接触面积越大，相应的就增加了轮胎与地面的摩擦力，车辆的动能转化为摩擦热能而损失的能量会增加，如若行驶相同距离时宽胎就更容易耗油。不过事物都有它的两面性，虽然油耗增加，但宽胎的抓地力要更强，进而也将获得更好的车身稳定性。
扁平比，是影响车辆对路面的反应灵敏度的主要因素。扁平比越低的车辆，胎壁越薄，且轮胎承受的压力亦越大，其对路面的反应非常灵敏，从而能够迅速把路面的信号传递给驾驶者，更便于操控，多见于一些以性能操控见长的车型。扁平比越高，胎壁越厚，虽然拥有充裕的缓冲厚度，但对路面的感觉较差，特别是转弯时会相对更为拖沓，多见于一些以舒适性见长的车型。还有就是越野车的扁平比一般较高，主要是为了适应环境恶劣的路况。
轮胎类型代号，常见的表示有“X”高压胎，“R”、“Z”子午胎，“一”低压胎。市场上的轿车一般采用子午线轮胎，且目前已经实现了子午线轮胎无内胎，俗称“原子胎”。这种轮胎在高速行驶中不易聚热，当轮胎受到钉子或尖锐物穿破后，漏气缓慢，可继续行驶一段距离。另外，原子胎还有简化生产工艺，减轻重量，节约原料等好处。 负荷指数是把一条轮胎所能承受的最大负荷以代号的形式表示，来表征轮胎承受负荷的能力，数值越大，轮胎所能承受的负荷也越大。负荷指数及对应承载质量列表如下。
毕业论文写作要求与格式规范 关于《毕业论文写作要求与格式规范》，是我们特意为大家整理的，希望对大家有所帮助。 (一)文体 毕业论文文体类型一般分为：试验论文、专题论文、调查报告、文献综述、个案评述、计算设计等。学生根据自己的实际情况，可以选择适合的文体写作。 (二)文风 符合科研论文写作的基本要求：科学性、创造性、逻辑性、
实用性、可读性、规范性等。写作态度要严肃认真，论证主题应有一定理论或应用价值;立论应科学正确，论据应充实可靠，结构层次应清晰合理，推理论证应逻辑严密。行文应简练，文笔应通顺，文字应朴实，撰写应规范，要求使用科研论文特有的科学语言。 (三)论文结构与排列顺序 毕业论文，一般由封面、独创性声明及版权授权书、摘要、目录、正文、后记、参考文献、附录等部分组成并按前后顺序排列。 1.封面：毕业论文(设计)封面具体要求如下： (1)论文题目应能概括论文的主要内容，切题、简洁，不超过30字，可分两行排列;
(2)层次：大学本科、大学专科 (3)专业名称：机电一体化技术、计算机应用技术、计算机网络技术、数控技术、模具设计与制造、电子信息、电脑艺术设计、会计电算化、商务英语、市场营销、电子商务、生物技术应用、设施农业技术、园林工程技术、中草药栽培技术和畜牧兽医等专业，应按照标准表述填写; (4)日期：毕业论文(设计)完成时间。 2.独创性声明和关于论文使用授权的说明：需要学生本人签字。 3.摘要：论文摘要的字数一般为300字左右。摘要是对论文的内容不加注释和评论的简短陈述，是文章内容的高度概括。主要内容包括：该项研究工作的内容、目的及其重要性;所使用的实验方法;总结研究成果，突出作者的新见解;研究结论及其意义。摘要中不列举例证，不描述研究过程，不做自我评价。
Backside setting/Back spacing - The measurement from the mounting pad to the inner edge of the wheel. 后距：安装盘到轮毂内侧轮缘边的距离。 Bead seat - The position where the tire rests and seals on the inside of the rim. 胎圈座：轮辋上安放轮胎的地方。 Bolt Circle - The diameter of an imaginary circle drawn through the center of each lug hole. Also referred to as the bolt pattern. 节圆：一个假想的圆的直径，该圆的圆周经过每一个螺栓孔的中心。也叫螺栓模式。 Center Bore - The hole in the center of the wheel machined to match the hub of specified vehicles with hub-centric wheels and machined to a generic size with lug centric wheels. 中心孔：在轮毂的中心加工的一个孔。在以中心孔定心时与轮轴适配，在以螺栓孔定心时为一通常尺寸。 Hub centric - The center bore hole of a wheel matches the hub diameter of the vehicle. This centers the wheel via the center hole rather than the lug nuts. 轮轴定心：轮毂中心孔与轮轴直径适配。通过中心孔定心，而不是通过螺栓孔定心。 Hub centric ring(s) - A nylon insert for the center bore of the wheel that keeps the wheel concentric to the vehicle's hub during installation. 轮毂中心环：一个嵌入轮毂中心孔的尼龙环，在安装时使轮毂与轮轴同心。 Load rating - The maximum weight that the wheel is designed to support. To determine load rating requirements take the gross axle weight ration and divide by 2. 载荷：轮毂的设计最大负载。等于轮轴总承重除以2。
公文格式规范与常见公文写作 一、公文概述与公文格式规范 党政机关公文种类的区分、用途的确定及格式规范等，由中共中央办公厅、国务院办公厅于2012年4月16日印发，2012年7月1日施行的《党政机关公文处理工作条例》规定。之前相关条例、办法停止执行。 （一）公文的含义 公文，即公务文书的简称，属应用文。 广义的公文，指党政机关、社会团体、企事业单位，为处理公务按照一定程序而形成的体式完整的文字材料。 狭义的公文，是指在机关、单位之间，以规范体式运行的文字材料，俗称“红头文件”。 ?（二）公文的行文方向和原则 ?、上行文下级机关向上级机关行文。有“请示”、“报告”、和“意见”。 ?、平行文同级机关或不相隶属机关之间行文。主要有“函”、“议案”和“意见”。 ?、下行文上级机关向下级机关行文。主要有“决议”、“决定”、“命令”、“公报”、“公告”、“通告”、“意见”、“通知”、“通报”、“批复”和“会议纪要”等。 ?其中，“意见”、“会议纪要”可上行文、平行文、下行文。?“通报”可下行文和平行文。 ?原则： ?、根据本机关隶属关系和职权范围确定行文关系 ?、一般不得越级行文 ?、同级机关可以联合行文 ?、受双重领导的机关应分清主送机关和抄送机关 ?、党政机关的部门一般不得向下级党政机关行文 ?(三) 公文的种类及用途 ?、决议。适用于会议讨论通过的重大决策事项。 ?、决定。适用于对重要事项作出决策和部署、奖惩有关单位和人员、变更或撤销下级机关不适当的决定事项。
?、命令（令）。适用于公布行政法规和规章、宣布施行重大强制性措施、批准授予和晋升衔级、嘉奖有关单位和人员。 ?、公报。适用于公布重要决定或者重大事项。 ?、公告。适用于向国内外宣布重要事项或者法定事项。 ?、通告。适用于在一定范围内公布应当遵守或者周知的事项。?、意见。适用于对重要问题提出见解和处理办法。 ?、通知。适用于发布、传达要求下级机关执行和有关单位周知或者执行的事项，批转、转发公文。 ?、通报。适用于表彰先进、批评错误、传达重要精神和告知重要情况。 ?、报告。适用于向上级机关汇报工作、反映情况，回复上级机关的询问。 ?、请示。适用于向上级机关请求指示、批准。 ?、批复。适用于答复下级机关请示事项。 ?、议案。适用于各级人民政府按照法律程序向同级人民代表大会或者人民代表大会常务委员会提请审议事项。 ?、函。适用于不相隶属机关之间商洽工作、询问和答复问题、请求批准和答复审批事项。 ?、纪要。适用于记载会议主要情况和议定事项。?（四）、公文的格式规范 ?、眉首的规范 ?（）、份号 ?也称编号，置于公文首页左上角第行，顶格标注。“秘密”以上等级的党政机关公文，应当标注份号。 ?（）、密级和保密期限 ?分“绝密”、“机密”、“秘密”三个等级。标注在份号下方。?（）、紧急程度 ?分为“特急”和“加急”。由公文签发人根据实际需要确定使用与否。标注在密级下方。 ?（）、发文机关标志（或称版头） ?由发文机关全称或规范化简称加“文件”二字组成。套红醒目，位于公文首页正中居上位置（按《党政机关公文格式》标准排
ctex宏包说明 https://www.doczj.com/doc/75927351.html,? 版本号：v1.02c修改日期：2011/03/11 摘要 ctex宏包提供了一个统一的中文L A T E X文档框架，底层支持CCT、CJK和xeCJK 三种中文L A T E X系统。ctex宏包提供了编写中文L A T E X文档常用的一些宏定义和命令。 ctex宏包需要CCT系统或者CJK宏包或者xeCJK宏包的支持。主要文件包括ctexart.cls、ctexrep.cls、ctexbook.cls和ctex.sty、ctexcap.sty。 ctex宏包由https://www.doczj.com/doc/75927351.html,制作并负责维护。 目录 1简介2 2使用帮助3 2.1使用CJK或xeCJK (3) 2.2使用CCT (3) 2.3选项 (4) 2.3.1只能用于文档类的选项 (4) 2.3.2只能用于文档类和ctexcap.sty的选项 (4) 2.3.3中文编码选项 (4) 2.3.4中文字库选项 (5) 2.3.5CCT引擎选项 (5) 2.3.6排版风格选项 (5) 2.3.7宏包兼容选项 (6) 2.3.8缺省选项 (6) 2.4基本命令 (6) 2.4.1字体设置 (6) 2.4.2字号、字距、字宽和缩进 (7) ?https://www.doczj.com/doc/75927351.html, 1
1简介2 2.4.3中文数字转换 (7) 2.5高级设置 (8) 2.5.1章节标题设置 (9) 2.5.2部分修改标题格式 (12) 2.5.3附录标题设置 (12) 2.5.4其他标题设置 (13) 2.5.5其他设置 (13) 2.6配置文件 (14) 3版本更新15 4开发人员17 1简介 这个宏包的部分原始代码来自于由王磊编写cjkbook.cls文档类，还有一小部分原始代码来自于吴凌云编写的GB.cap文件。原来的这些工作都是零零碎碎编写的，没有认真、系统的设计，也没有用户文档，非常不利于维护和改进。2003年，吴凌云用doc和docstrip工具重新编写了整个文档，并增加了许多新的功能。2007年，oseen和王越在ctex宏包基础上增加了对UTF-8编码的支持，开发出了ctexutf8宏包。2009年5月，我们在Google Code建立了ctex-kit项目1，对ctex宏包及相关宏包和脚本进行了整合，并加入了对XeT E X的支持。该项目由https://www.doczj.com/doc/75927351.html,社区的开发者共同维护，新版本号为v0.9。在开发新版本时，考虑到合作开发和调试的方便，我们不再使用doc和docstrip工具，改为直接编写宏包文件。 最初Knuth设计开发T E X的时候没有考虑到支持多国语言，特别是多字节的中日韩语言。这使得T E X以至后来的L A T E X对中文的支持一直不是很好。即使在CJK解决了中文字符处理的问题以后，中文用户使用L A T E X仍然要面对许多困难。最常见的就是中文化的标题。由于中文习惯和西方语言的不同，使得很难直接使用原有的标题结构来表示中文标题。因此需要对标准L A T E X宏包做较大的修改。此外，还有诸如中文字号的对应关系等等。ctex宏包正是尝试着解决这些问题。中间很多地方用到了在https://www.doczj.com/doc/75927351.html,论坛上的讨论结果，在此对参与讨论的朋友们表示感谢。 ctex宏包由五个主要文件构成：ctexart.cls、ctexrep.cls、ctexbook.cls和ctex.sty、ctexcap.sty。ctex.sty主要是提供整合的中文环境，可以配合大多数文档类使用。而ctexcap.sty则是在ctex.sty的基础上对L A T E X的三个标准文档类的格式进行修改以符合中文习惯，该宏包只能配合这三个标准文档类使用。ctexart.cls、ctexrep.cls、ctexbook.cls则是ctex.sty、ctexcap.sty分别和三个标准文档类结合产生的新文档类，除了包含ctex.sty、ctexcap.sty的所有功能，还加入了一些修改文档类缺省设置的内容（如使用五号字体为缺省字体）。 1https://www.doczj.com/doc/75927351.html,/p/ctex-kit/
改装升级轮毂和轮胎（适合所有车型）相关知识(2009-01-12 21:00:42) 标签：升级轮毂轮胎车型汽车分类：LIBERTYJEEP 轮毂和轮胎的改装 这一阵子很多同学都在改装升级轮毂和轮胎，一个看似简单的改装还是有很多学问的，就像我们穿鞋一样如果不合适很难受还会造成损伤。言归正传，首先我们先来了解几组和轮毂相关的关键数据。找了一张图还算比较清楚 1、节圆直径（PCD）：必须一致的安装参数。越野车多为6×139.7mm，大排量的车型5孔较为合理，咱们的Jeep一般都是5孔。 2、偏距（OFFSET/ET）：偏距有正偏距、零偏距及负偏距之分。偏距变小轮距也就变大，升级轮圈后根据轮辋宽度不同以及偏距的变化，轮距会随之改变。如果升级了轮辋，将要考虑车轮是否会和里面避震器和悬架零件，以及外面的挡泥板是否会干涉（这方面知识将在后面图解）。合适的偏距大小可以确保车轮不会发生干涉。 3、X距（X-FACTOR）：要有一定的空间，否则会干涉制动器。 4、中心孔（HUB HOLE/CB）：各车都不一样，如果车轮的中心孔过大，一定要用中心孔套环，否则高速行驶时车会抖动。 5、Backspacing：安装位至轮毂后切线距离，美规通常标注的数值。 首先测算自己车的偏距：把轮毂放平外面朝下（是否安装轮胎无所谓），测量高度除以2 得到中心线，即零值位置。再用一个平尺放在轮胎上面测量安装孔到平尺的距离，用这个数减去中心线，即得到偏距（offset/et）。是合算有车型。大家可以自己动手测一下得到数据。Offest的数值通常在美规数据中查不到，如何得到这个数据呢？举例说明美规的轮毂通常标注：17×9 backspacing：5，我们这样来测算：17×9中的17为轮毂直径17英寸，9为轮毂宽度9 英寸，不难得出轮毂的中心线（0值）为4.5英寸（这个数如果不知道怎么算出来的，我就。。。）如上图backspacing：5为5英寸，用中心线4.5英寸减去5英寸=0.5英寸（大约1.27cm）这个数据就是Offset的数值。 大家在选择轮毂的时候一定要根据实际情况，另外，要配合好相应的轮胎。给大家一个表如果换大轮胎一定要对照好。【注意】轮胎轮辋的配合超出许可的
学生会文档书写格式规范要求 目前各部门在日常文书编撰中大多按照个人习惯进行排版，文档中字体、文字大小、行间距、段落编号、页边距、落款等参数设置不规范，严重影响到文书的标准性和美观性，以下是文书标准格式要求及日常文档书写注意事项，请各部门在今后工作中严格实行： 一、文件要求 1.文字类采用Word格式排版 2.统计表、一览表等表格统一用Excel格式排版 3.打印材料用纸一般采用国际标准A4型（210mm×297mm），左侧装订。版面方向以纵向为主，横向为辅，可根据实际需要确定 4.各部门的职责、制度、申请、请示等应一事一报，禁止一份行文内同时表述两件工作。 5.各类材料标题应规范书写，明确文件主要内容。 二、文件格式 （一）标题 1.文件标题：标题应由发文机关、发文事由、公文种类三部分组成，黑体小二号字,不加粗，居中，段后空1行。 （二）正文格式 1. 正文字体：四号宋体，在文档中插入表格，单元格内字体用宋体，字号可根据内容自行设定。 2.页边距：上下边距为2.54厘米；左右边距为 3.18厘米。
3.页眉、页脚：页眉为1.5厘米；页脚为1.75厘米； 4.行间距：1.5倍行距。 5.每段前的空格请不要使用空格，应该设置首先缩进2字符 6.年月日表示：全部采用阿拉伯数字表示。 7.文字从左至右横写。 （三）层次序号 (1)一级标题：一、二、三、 (2)二级标题：（一）（二）（三） (3)三级标题：1. 2. 3. (4)四级标题：（1）（2）（3） 注：三个级别的标题所用分隔符号不同，一级标题用顿号“、”例如：一、二、等。二级标题用括号不加顿号，例如：（三）（四）等。三级标题用字符圆点“.”例如：5. 6.等。 （四）、关于落款： 1.对外行文必须落款“湖南环境生物专业技术学院学生会”“校学生会”各部门不得随意使用。 2.各部门文件落款需注明组织名称及部门“湖南环境生物专业技术学院学生会XX部”“校学生会XX部” 3.所有行文落款不得出现“环境生物学院”“湘环学院”“学生会”等表述不全的简称。 4.落款填写至文档末尾右对齐，与前一段间隔2行 5.时间落款：文档中落款时间应以“2016年5月12日”阿拉伯数字
轮胎升级规格对照表 想要做轮胎升级的车主来说，最重要的，当然就是要确认自己轮胎可以升级到多大的规格；有一个最简单的原则，那就是升级之后的轮胎规格，整个直径与原先轮胎的“直径数据”之差必须控制在〝3%〞之内，以下我们就来以实例试算看看： 若是以185/60R14的规格为例，原先的侧边直径尺寸如下： 轮辋：14英寸，14英寸×2.54厘米=35.56厘米 胎侧：胎面的60%，18.5厘米×0.6=11.1厘米 但是因为轮辋上下各有一胎侧，所以要乘以2 胎侧：11.1厘米×2=22.2厘米 直径：35.56厘米+22.2厘米=57.76厘米 如果想要升级成为195/50R15这样的较大规格，可以吗？ 轮辋：15英寸，15英寸×2.54厘米=38.1厘米 胎侧：胎面的50%，19.5厘米×0.5=9.75厘米， 但是因为轮辋上下各有一胎侧，所以要乘以2 胎侧：9.75厘米×2=19.5厘米 直径：38.1厘米+19.5厘米=57.6厘米 与185/60R14规格轮胎的57.76厘米相比，差值仅在0.3%，可说是轮胎升级的最正确数字，而如果只想要加宽胎面，但是不想变更轮胎的扁平比，也就是选用195/60R14规格的轮胎，会有什么后果呢？ 轮辋：14英寸，14英寸×2.54厘米=35.56厘米 胎侧：胎面的60%，18.5厘米×0.6=11.7厘米再×2=23.4厘米 直径：35.56厘米+23.4厘米=58.96厘米 与185/60R14规格轮胎的57.76厘米相比，差值已经达到2%，基本上还是在误差容许范围之内，但是因为直径变大了，整个轮胎的圆周也就变长了，因此速度码表会变得不准，里程表也会跟着失准；而最重要的是，变宽之后的轮胎胎面在方向盘打到极左或极右的死点时，是否会顶到轮拱的内缘，如果情况严重，甚至会导致定位偏离及轮胎异常磨耗的现象，想要轮胎升级的车迷们千万要留意这一点。
政府公文写作格式 一、眉首部分 （一）发文机关标识 平行文和下行文的文件头，发文机关标识上边缘至上页边为62mm，发文机关下边缘至红色反线为28mm。 上行文中，发文机关标识上边缘至版心上边缘为80mm，即与上页边距离为117mm，发文机关下边缘至红色反线为30mm。 发文机关标识使用字体为方正小标宋_GBK，字号不大于22mm×15mm。 （二）份数序号 用阿拉伯数字顶格标识在版心左上角第一行，不能少于2位数。标识为“编号000001” （三）秘密等级和保密期限 用3号黑体字顶格标识在版心右上角第一行，两字中间空一字。如需要加保密期限的，密级与期限间用“★”隔开，密级中则不空字。 （四）紧急程度 用3号黑体字顶格标识在版心右上角第一行，两字中间空一字。如同时标识密级，则标识在右上角第二行。 （五）发文字号 标识在发文机关标识下两行，用3号方正仿宋_GBK字体剧
中排布。年份、序号用阿拉伯数字标识，年份用全称，用六角括号“〔〕”括入。序号不用虚位，不用“第”。发文字号距离红色反线4mm。 （六）签发人 上行文需要标识签发人，平行排列于发文字号右侧，发文字号居左空一字，签发人居右空一字。“签发人”用3号方正仿宋_GBK，后标全角冒号，冒号后用3号方正楷体_GBK标识签发人姓名。多个签发人的，主办单位签发人置于第一行，其他从第二行起排在主办单位签发人下，下移红色反线，最后一个签发人与发文字号在同一行。 二、主体部分 （一）标题 由“发文机关+事由+文种”组成，标识在红色反线下空两行，用2号方正小标宋_GBK，可一行或多行居中排布。 （二）主送机关 在标题下空一行，用3号方正仿宋_GBK字体顶格标识。回行是顶格，最后一个主送机关后面用全角冒号。 （三）正文 主送机关后一行开始，每段段首空两字，回行顶格。公文中的数字、年份用阿拉伯数字，不能回行，阿拉伯数字：用3号Times New Roman。正文用3号方正仿宋_GBK，小标题按照如下排版要求进行排版：
tabularx宏包中改变弹性列的宽度\hsize 分类：latex 2012-03-07 21:54 12人阅读评论(0) 收藏编辑删除 \documentclass{article} \usepackage{amsmath} \usepackage{amssymb} \usepackage{latexsym} \usepackage{CJK} \usepackage{tabularx} \usepackage{array} \newcommand{\PreserveBackslash}[1]{\let \temp =\\#1 \let \\ = \temp} \newcolumntype{C}[1]{>{\PreserveBackslash\centering}p{#1}} \newcolumntype{R}[1]{>{\PreserveBackslash\raggedleft}p{#1}} \newcolumntype{L}[1]{>{\PreserveBackslash\raggedright}p{#1}} \begin{document} \begin{CJK*}{GBK}{song} \CJKtilde \begin{tabularx}{10.5cm}{|p{3cm} |>{\setlength{\hsize}{.5\hsize}\centering}X |>{\setlength{\hsize}{1.5\hsize}}X|} %\hsize是自动计算的列宽度，上面{.5\hsize}与{1.5\hsize}中的\hsize前的数字加起来必须等于表格的弹性列数量。对于本例，弹性列有2列，所以“.5+1.5=2”正确。 %共3列，总列宽为10.5cm。第1列列宽为3cm，第3列的列宽是第2列列宽的3倍，其宽度自动计算。第2列文字左右居中对齐。注意：\multicolum命令不能跨越X列。 \hline 聪明的鱼儿在咬钩前常常排祠再三& 这是因为它们要荆断食物是否安全&知果它们认为有危险\\ \hline 它们枕不会吃& 如果它们判定没有危险& 它们就食吞钩\\ \hline 一眼识破诱饵的危险，却又不由自主地去吞钩的& 那才正是人的心理而不是鱼的心理& 是人的愚合而不是鱼的恳奋\\
广州中医药大学研究生学位论文基本要求与写作规范 为了进一步提高学位工作水平和学位论文质量，保证我校学位论文在结构和格式上的规范与统一，特做如下规定： 一、学位论文基本要求 （一）科学学位硕士论文要求 1.论文的基本科学论点、结论，应在中医药学术上和中医药科学技术上具有一定的理论意义和实践价值。 2.论文所涉及的内容，应反映出作者具有坚实的基础理论和系统的专门知识。 3.实验设计和方法比较先进，并能掌握本研究课题的研究方法和技能。 4.对所研究的课题有新的见解。 5.在导师指导下研究生独立完成。 6.论文字数一般不少于3万字，中、英文摘要1000字左右。 （二）临床专业学位硕士论文要求 临床医学硕士专业学位申请者在临床科研能力训练中学会文献检索、收集资料、数据处理等科学研究的基本方法,培养临床思维能力与分析能力,完成学位论文。 1.学位论文包括病例分析报告及文献综述。 2.学位论文应紧密结合中医临床或中西结合临床实际，以总结临床实践经验为主。 3.学位论文应表明申请人已经掌握临床科学研究的基本方法。 4.论文字数一般不少于15000字，中、英文摘要1000字左右。 （三）科学学位博士论文要求 1.研究的课题应在中医药学术上具有较大的理论意义和实践价值。 2.论文所涉及的内容应反映作者具有坚实宽广的理论基础和系统深入的专门知识，并表明作者具有独立从事科学研究工作的能力。 3.实验设计和方法在国内同类研究中属先进水平，并能独立掌握本研究课题的研究方法和技能。
4.对本研究课题有创造性见解，并取得显著的科研成果。 5.学位论文必须是作者本人独立完成，与他人合作的只能提出本人完成的部分。 6.论文字数不少于5万字，中、英摘要3000字；详细中文摘要(单行本)1万字左右。 （四）临床专业学位博士论文要求 1.要求论文课题紧密结合中医临床或中西结合临床实际，研究结果对临床工作具有一定的应用价值。 2.论文表明研究生具有运用所学知识解决临床实际问题和从事临床科学研究的能力。 3.论文字数一般不少于3万字，中、英文摘要2000字；详细中文摘要(单行本)5000字左右。 二、学位论文的格式要求 （一）学位论文的组成 博士、硕士学位论文一般应由以下几部分组成，依次为：1.论文封面；2. 原创性声明及关于学位论文使用授权的声明；3.中文摘要；4.英文摘要；5.目录； 6.引言； 7.论文正文； 8.结语； 9.参考文献；10.附录；11.致谢。 1.论文封面：采用研究生处统一设计的封面。论文题目应以恰当、简明、引人注目的词语概括论文中最主要的内容。避免使用不常见的缩略词、缩写字，题名一般不超过30个汉字。论文封面“指导教师”栏只写入学当年招生简章注明、经正式遴选的指导教师1人，协助导师名字不得出现在论文封面。 2．原创性声明及关于学位论文使用授权的声明（后附）。 3.中文摘要：要说明研究工作目的、方法、成果和结论。并写出论文关键词3～5个。 4.英文摘要：应有题目、专业名称、研究生姓名和指导教师姓名，内容与中文提要一致，语句要通顺，语法正确。并列出与中文对应的论文关键词3～5个。 5.目录：将论文各组成部分(1～3级)标题依次列出，标题应简明扼要，逐项标明页码，目录各级标题对齐排。 6.引言：在论文正文之前，简要说明研究工作的目的、范围、相关领域前人所做的工作和研究空白，本研究理论基础、研究方法、预期结果和意义。应言简
（公文写作）毕业论文写作要求和格式规范
中国农业大学继续教育学院 毕业论文写作要求和格式规范 壹、写作要求 （壹）文体 毕业论文文体类型壹般分为：试验论文、专题论文、调查方案、文献综述、个案评述、计算设计等。学生根据自己的实际情况，能够选择适合的文体写作。 （二）文风 符合科研论文写作的基本要求：科学性、创造性、逻辑性、实用性、可读性、规范性等。写作态度要严肃认真，论证主题应有壹定理论或应用价值；立论应科学正确，论据应充实可靠，结构层次应清晰合理，推理论证应逻辑严密。行文应简练，文笔应通顺，文字应朴实，撰写应规范，要求使用科研论文特有的科学语言。 （三）论文结构和排列顺序 毕业论文，壹般由封面、独创性声明及版权授权书、摘要、目录、正文、后记、参考文献、附录等部分组成且按前后顺序排列。 1．封面：毕业论文（设计）封面（见文件5）具体要求如下： （1）论文题目应能概括论文的主要内容，切题、简洁，不超过30字，可分俩行排列； （2）层次：高起本，专升本，高起专； （3）专业名称：现开设园林、农林经济管理、会计学、工商管理等专业，应按照标准表述填写； （4）密级：涉密论文注明相应保密年限； （5）日期：毕业论文完成时间。 2．独创性声明和关于论文使用授权的说明：（略）。
3．摘要：论文摘要的字数壹般为300字左右。摘要是对论文的内容不加注释和评论的简短陈述，是文章内容的高度概括。主要内容包括：该项研究工作的内容、目的及其重要性；所使用的实验方法；总结研究成果，突出作者的新见解；研究结论及其意义。摘要中不列举例证，不描述研究过程，不做自我评价。 论文摘要后另起壹行注明本文的关键词，关键词是供检索用的主题词条，应采用能够覆盖论文内容的通用专业术语，符合学科分类，壹般为3～5个，按照词条的外延层次从大到小排列。 4．目录（目录示例见附件3）：独立成页，包括论文中的壹级、二级标题、后记、参考文献、和附录以及各项所于的页码。 5．正文：包括前言、论文主体和结论 前言：为正文第壹部分内容，简单介绍本项研究的背景和国内外研究成果、研究现状，明确研究目的、意义以及要解决的问题。 论文主体：是全文的核心部分，于正文中应将调查、研究中所得的材料和数据加工整理和分析研究，提出论点，突出创新。内容可根据学科特点和研究内容的性质而不同。壹般包括：理论分析、计算方法、实验装置和测试方法、对实验结果或调研结果的分析和讨论，本研究方法和已有研究方法的比较等方面。内容要求论点正确，推理严谨，数据可靠，文字精炼，条理分明，重点突出。 结论：为正文最后壹部分，是对主要成果的归纳和总结，要突出创新点，且以简练的文字对所做的主要工作进行评价。 6．后记：对整个毕业论文工作进行简单的回顾总结，对给予毕业论文工作提供帮助的组织或个人表示感谢。内容应尽量简单明了，壹般为200字左右。 7．参考文献：是论文不可或缺的组成部分。它既可反映毕业论文工作中取材广博程度，又可反映文稿的科学依据和作者尊重他人研究成果的严肃态度，仍能够向读者提供有关
车轮基础知识 一、车轮的术语： 1.车轮：又叫“轮毂”或“轮圈”，台湾同胞还有一种叫法是“胎铃”，是汽车的重要行驶部件。 2.车轮（wheel）：轮胎和车轴之间的旋转承载件，通常由轮辋和轮辐两个主要部件组成，轮辋和轮 辐可是整体的、永久连接的或可拆卸的。 整体的永久链接的可拆卸的 3.轮辋：车轮上安装和支承轮胎的部件。 4.轮辐：车轮上介于车桥和轮辋之间的支承部件。 5.挡圈：可以从轮辋上拆卸下来的轮缘，能起锁圈作用的。 6.偏距：轮辐安装平面到轮辋中心平面的距离。 7.内偏距车轮：结构为轮辋中心平面位于轮辐安装平面内侧的车轮。 8.零偏距车轮：结构为轮辋中心平面和轮辐安装平面重合的车轮。 9.外偏距车轮：结构为轮辋中心平面位于轮辐安装平面外侧的车轮。 10.双式车轮：一个具有足够内偏距和必要轮廓形状的车轮，当两个这样的车轮彼此安装在一起时，在 车桥的一端能支承两个车轮。 11.双轮中心距：车轮成对安装时构成所要求的双胎间距的两轮辋中心平面之间的距离。 12.轮辋体：轮辋主体部分。 13.轮缘：轮辋上给轮胎提供轴向支承的部分。 14.胎圈座：轮辋上给轮胎提供径向支承的部分。
15.轮辋槽：轮辋底部具有足够深度和宽度的凹槽，可以使轮胎胎圈越过轮辋安装侧的轮缘和胎圈座斜 面进行安装或拆卸。 16.锁圈槽：轮辋体上用以安放锁圈或弹性挡圈并以槽顶对其限位的沟槽。 17.锁圈：对挡圈或座圈起锁止作用的座落在锁圈槽内的弹性圈。 18.座圈：可以从轮辋体上拆卸下来的胎圈座。 19.轮辋主要的几个名称及位置： A B P G H β A B G P P S P D β D 二、车轮的类别： ?按材质分：钢制车轮、铝合金车轮和镁合金车轮等三大类。其中，钢制车轮和铝合金车轮是最为常见的汽车车轮，高端车或者高配车型一般全部用铝合金轮毂，低档或者低配车型的则大都使用钢制轮毂，而镁合金车轮在汽车行业刚刚起步，使用该种轮毂的汽车很少，其主要的应用行业是摩托车行业。 ?按照类型分为：辐板式车轮、辐条式车轮、对开式车轮、组装轮辋式车轮、可反装式车轮、和可调式车轮。 辐板式车轮辐条式车轮对开式车轮