# 0.6 Regularity, moments, and wavelet system design  (Page 9/13)

 Page 9 / 13

An illustration of the effects of these approximations on a signal is shown in [link] where a signal with a very smooth component (a sinusoid) and a discontinuous component (a square wave) is expanded in awavelet series using samples as the high resolution scaling function coefficients. Notice the effects of projecting onto lower and lowerresolution scales.

If we consider a wavelet system where the same number of scaling function and wavelet moments are set zero and this number is as large as possible,then the following is true [link] , [link] :

Theorem 27 If $m\left(\ell \right)={m}_{1}\left(\ell \right)=0$ for $\ell =1,2,\cdots ,L$ and ${m}_{1}\left(0\right)=0$ , then the ${L}^{2}$ error is

${ϵ}_{3}=\parallel f\left(t\right)-{S}^{j}\left\{f\left(t\right)\right\}{\parallel }_{2}\phantom{\rule{0.166667em}{0ex}}\le \phantom{\rule{0.166667em}{0ex}}{C}_{3}\phantom{\rule{0.166667em}{0ex}}{2}^{-j\left(L+1\right)},$

where ${C}_{3}$ is a constant independent of $j$ and $L$ , but dependent on $f\left(t\right)$ and the wavelet system.

Here we see that for this wavelet system called a Coifman wavelet system, that using samples as the inner product expansion coefficients is anexcellent approximation. This justifies that using samples of a signal as input to a filter bank gives a proper wavelet analysis. This approximationis also illustrated in [link] and in [link] .

From the previous approximation theorems, we see that a combination of zero wavelet and zero scaling function moments used with samples of thesignal may give superior results to wavelets with only zero wavelet moments. Not only does forcing zero scaling function moments give abetter approximation of the expansion coefficients by samples, it often causesthe scaling function to be more symmetric. Indeed, that characteristic may be more important than the sample approximation in certainapplications.

Daubechies considered the design of these wavelets which were suggested by Coifman [link] , [link] , [link] . Gopinath [link] , [link] and Wells [link] , [link] show how zero scaling function moments give a better approximation of high-resolution scaling coefficients by samples. Tianand Wells [link] , [link] have also designed biorthogonal systems with mixed zero moments with very interesting properties.

The Coifman wavelet system (Daubechies named the basis functions “coiflets") is an orthonormal multiresolution wavelet system with

$\int {t}^{k}\phi \left(t\right)\phantom{\rule{0.166667em}{0ex}}dt=m\left(k\right)=0,\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\text{for}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}k=1,2,\cdots ,L-1$
$\int {t}^{k}\psi \left(t\right)\phantom{\rule{0.166667em}{0ex}}dt={m}_{1}\left(k\right)=0,\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\text{for}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}\phantom{\rule{4pt}{0ex}}k=1,2,\cdots ,L-1.$

This definition imposes the requirement that there be at least $L-1$ zero scaling function moments and at least $L-1$ wavelet moments in addition to the one zero moment of ${m}_{1}\left(0\right)$ required by orthogonality. This system is said to be of order or degree $L$ and sometime has the additional requirement that the length of the scaling function filter $h\left(n\right)$ , which is denoted $N$ , is minimum [link] , [link] . In the design of these coiflets, one obtains more total zero moments than $N/2-1$ . This was first noted by Beylkin, et al [link] . The length-4 wavelet systemhas only one degree of freedom, so it cannot have both a scaling function moment and wavelet moment of zero (see [link] ). Tian [link] , [link] has derived formulas for four length-6 coiflets. These are:

$h=\left[\frac{-3+\sqrt{7}}{16\sqrt{2}},,,\frac{1-\sqrt{7}}{16\sqrt{2}},,,\frac{7-\sqrt{7}}{8\sqrt{2}},,,\frac{7+\sqrt{7}}{8\sqrt{2}},,,\frac{5+\sqrt{7}}{16\sqrt{2}},,,\frac{1-\sqrt{7}}{16\sqrt{2}}\right],$

or

$h=\left[\frac{-3-\sqrt{7}}{16\sqrt{2}},,,\frac{1+\sqrt{7}}{16\sqrt{2}},,,\frac{7+\sqrt{7}}{8\sqrt{2}},,,\frac{7-\sqrt{7}}{8\sqrt{2}},,,\frac{5-\sqrt{7}}{16\sqrt{2}},,,\frac{1+\sqrt{7}}{16\sqrt{2}}\right],$

or

$h=\left[\frac{-3+\sqrt{15}}{16\sqrt{2}},,,\frac{1-\sqrt{15}}{16\sqrt{2}},,,\frac{3-\sqrt{15}}{8\sqrt{2}},,,\frac{3+\sqrt{15}}{8\sqrt{2}},,,\frac{13+\sqrt{15}}{16\sqrt{2}},,,\frac{9-\sqrt{15}}{16\sqrt{2}}\right],$

or

$h=\left[\frac{-3-\sqrt{15}}{16\sqrt{2}},,,\frac{1+\sqrt{15}}{16\sqrt{2}},,,\frac{3+\sqrt{15}}{8\sqrt{2}},,,\frac{3-\sqrt{15}}{8\sqrt{2}},,,\frac{13-\sqrt{15}}{16\sqrt{2}},,,\frac{9+\sqrt{15}}{16\sqrt{2}}\right],$

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Got questions? Join the online conversation and get instant answers!