On Apr 12, 3:39*pm, Cecil Moore wrote:
Keith Dysart wrote:
It would be helpful, however, if you could actually demonstrate a
system where the energies balance, but the flows do not.

That's obviously easy to demonstrate in a distributed
network system. We can have energy flowing into both
ends of a loading coil at the same time and 180 degrees
later, energy flowing out of both ends at the same time.
The energies balance but the flows are completely
unbalanced and indeed defy the lumped circuit model.

You are not quite looking at the system correctly.

It is a system with two ports (bottom and top) where
energy can enter or leave, and one element (coil)
which can store energy.

The energy that flows in the bottom either flows out
the top or increases the energy stored in the coil.
The energy flowing into the bottom is equal to
the sum of the energy flowing out the top plus the
increase in the energy stored in the coil.
Expressed arithmetically
Pbottom(t) = Pcoil(t) + Ptop(t)

For the specific situation you describe above:
"energy flowing out of both ends at the same time"
means that the energy stored in the ooil is being
reduced to supply the energy leaving the top and
the bottom. The sum of the energy flows out of
the top and the bottom is exactly equal to the rate
at which the stored energy is being reduced.

Lumped or not lumped is moot.
The same analysis can be applied to a transmission
line. The energy flow into the left is exactly
equal to the energy flow out on the right plus
the rate of increase in the energy stored in the
line.

Energy flows (aka power) do indeed balance, though
you certainly have to correctly pick the flows that
should balance.

...Keith

Keith Dysart wrote:
For the specific situation you describe above:
"energy flowing out of both ends at the same time"
means that the energy stored in the ooil is being
reduced to supply the energy leaving the top and
the bottom. The sum of the energy flows out of
the top and the bottom is exactly equal to the rate
at which the stored energy is being reduced.

Yes, the energy obviously balances but the instantaneous
powers are in opposite directions and therefore cannot
balance.

Lumped or not lumped is moot.

Energy cannot flow out of both ends of a lumped circuit
inductor. The current is, by definition, exactly the
same at both ends as it is for the lumped inductors in
EZNEC. You might find these class notes informative.

http://www.ttr.com/corum/
--
73, Cecil http://www.w5dxp.com

On Apr 13, 9:45*am, Cecil Moore wrote:
Keith Dysart wrote:
For the specific situation you describe above:
"energy flowing out of both ends at the same time"
means that the energy stored in the ooil is being
reduced to supply the energy leaving the top and
the bottom. The sum of the energy flows out of
the top and the bottom is exactly equal to the rate
at which the stored energy is being reduced.

Yes, the energy obviously balances but the instantaneous
powers are in opposite directions and therefore cannot
balance.

Lumped or not lumped is moot.

Energy cannot flow out of both ends of a lumped circuit
inductor. The current is, by definition, exactly the
same at both ends as it is for the lumped inductors in
EZNEC. You might find these class notes informative.

It is well known that if one builds the wrong model one
will get the wrong answer. You build the wrong model,
then claim that flows do not balance. Unbalanced flows
are the expected result from incomplete models.

Your imcompleteness is that you forgot to include the
energy flow into the electric and magnetic fields around
the coil. When one does not forget this flow, all of
the flows will balance at every instant.

...Keith

Keith Dysart wrote:
Your imcompleteness is that you forgot to include the
energy flow into the electric and magnetic fields around
the coil. When one does not forget this flow, all of
the flows will balance at every instant.

Sorry, it may or may not be a coil. It is in a black box
whose contents are unknown. Including the energy flows
inside the black box is impossible. The instantaneous
power into the black box does not balance the instantaneous
power out of the black box.
--
73, Cecil http://www.w5dxp.com

On Apr 13, 8:41*pm, Cecil Moore wrote:
Keith Dysart wrote:
Your imcompleteness is that you forgot to include the
energy flow into the electric and magnetic fields around
the coil. When one does not forget this flow, all of
the flows will balance at every instant.

Sorry, it may or may not be a coil. It is in a black box
whose contents are unknown. Including the energy flows
inside the black box is impossible. The instantaneous
power into the black box does not balance the instantaneous
power out of the black box.

Black boxes are an excellent way to set problems which help us
learn about the meaning of theories.

Conservation of energy and its corollary, conservation of power,
is used in a different way for analyzing black boxes than it
is when we analyzed the fully specified circuit in your Fig 1-1.

With the black box, knowing the power function on the two ports,
we can compute the energy flow into the storage elements within
the box. If the flow out of one port is not always exactly
balanced by the flow into the other, then we know that the black
box is storing some energy and therefore that it has some elements
which store energy. In a more typical situation, we do not have
a completely black box, but we know some of its elements. We can
use the balance of energy flows to help us decide if we have all
the elements. If some of the energy flow is unaccounted for, then
we have not yet found all the elements.

If the box is truly opague, then all we can say is that it has
some energy storage elements and that collectively, the flow
into these elements is described by
Pport1(t) - Pport2(t)

The situation is somewhat different in Fig 1-1. All the elements
of the system are completely specified in Fig 1-1 and we used
circuit theory to compute the energy flows. Not surprisingly, they
completely balanced:
Ps(t) = Prs(t) + Pg(t)
Associated with Fig 1-1, there is a secondary hypothesis that it
should be possible to account for another energy flow, the imputed
flow in the reflected wave on the line. The inability to account
for this flow, given the conservation of power corollary to the
conservation of energy law, is a very strong indicator that the
energy flow imputed to the reflected wave is not an actual energy
flow.

...Keith

Keith Dysart wrote:
All the elements
of the system are completely specified in Fig 1-1 and we used
circuit theory to compute the energy flows. Not surprisingly, they
completely balanced:
Ps(t) = Prs(t) + Pg(t)

Yes, but that is only *NET* energy flow and says nothing
about component energy flow. Everything is already known
about net energy flow and there are no arguments about it
so you are wasting your time. Your equation above completely
ignores reflections which is the subject of the thread.

You object to me being satisfied with average energy flow
while you satisfy yourself with net energy flow. I don't see
one iota of conceptual difference between our two positions.

After hundreds of postings, all you have proved is that
Eugene Hecht was right when he said instantaneous powers
are "of limited utility", such that you cannot even tell
me how many joules there are in 100 watts of instantaneous
power when it is the quantity of those very joules that
are required to be conserved and not the 100 watts.

The limit in your quest for tracking instantaneous energy
is knowing the position and momentum of each individual
electron. Good luck on that one.

I am going to summarize the results of my Part 1 article
and be done with it.

In the special case presented in Part 1, there are only
two sources of power dissipation in the entire system,
the load resistor and the source resistor. None of the
reflected energy is dissipated in the load resistor
because the chosen special conditions prohibit reflections
from the source resistor. Therefore, all of the energy not
dissipated in the load resistor is dissipated in the source
resistor because there is no other source of dissipation
in the entire system. Only RL and Rs exist. Pr is not
dissipated in RL. Where is Pr dissipated? Even my ten year
old grandson can solve that problem and he's no future
rocket scientist.
--
73, Cecil http://www.w5dxp.com

On Mon, 14 Apr 2008 09:10:20 -0500
Cecil Moore wrote:

Keith Dysart wrote:
All the elements
of the system are completely specified in Fig 1-1 and we used
circuit theory to compute the energy flows. Not surprisingly, they
completely balanced:
Ps(t) = Prs(t) + Pg(t)

Yes, but that is only *NET* energy flow and says nothing
about component energy flow. Everything is already known
about net energy flow and there are no arguments about it
so you are wasting your time. Your equation above completely
ignores reflections which is the subject of the thread.

You object to me being satisfied with average energy flow
while you satisfy yourself with net energy flow. I don't see
one iota of conceptual difference between our two positions.

After hundreds of postings, all you have proved is that
Eugene Hecht was right when he said instantaneous powers
are "of limited utility", such that you cannot even tell
me how many joules there are in 100 watts of instantaneous
power when it is the quantity of those very joules that
are required to be conserved and not the 100 watts.

The limit in your quest for tracking instantaneous energy
is knowing the position and momentum of each individual
electron. Good luck on that one.

I am going to summarize the results of my Part 1 article
and be done with it.

In the special case presented in Part 1, there are only
two sources of power dissipation in the entire system,
the load resistor and the source resistor. None of the
reflected energy is dissipated in the load resistor
because the chosen special conditions prohibit reflections
from the source resistor. Therefore, all of the energy not
dissipated in the load resistor is dissipated in the source
resistor because there is no other source of dissipation
in the entire system. Only RL and Rs exist. Pr is not
dissipated in RL. Where is Pr dissipated? Even my ten year
old grandson can solve that problem and he's no future
rocket scientist.
--
73, Cecil http://www.w5dxp.com

This thread has one assumption that I find very frustrating, a voltage source that is a steady source of power but can not absorb power. My view is that any source must both absorb and deliver power at some none zero impedance. As justification for this view, I offer that current always flows from high voltage to lower voltage, so a real voltage source would have to absorb energy if the external voltage exceeded the voltage of the voltage source.

While it can be agrued that the ideal voltage source would have zero internal resistance, that argument does not address the fact that power flowing in the reverse direction (into the source, against the source supplied voltage) delivers power into the source. Charging a battery with zero internal resistance is a good example. Another example is the observation that a generator becomes a motor when the externally suppied voltage exceeds the voltage supplied by the generator.

Yes, we can make the assumption that the voltage source can not absorb power at any time, but the assumption takes us into an unreal world and gives answers that are impossible to duplicate with measurements. Some would call that a world of science fiction.
--
73, Roger, W7WKB

On Apr 14, 10:10*am, Cecil Moore wrote:
Keith Dysart wrote:
All the elements
of the system are completely specified in Fig 1-1 and we used
circuit theory to compute the energy flows. Not surprisingly, they
completely balanced:
* *Ps(t) = Prs(t) + Pg(t)

Yes, but that is only *NET* energy flow and says nothing
about component energy flow. Everything is already known
about net energy flow and there are no arguments about it
so you are wasting your time.

Ahhh, but there is then agreement that energy flows (power) must
be in balance to satisfy conservation of energy.

Your equation above completely
ignores reflections which is the subject of the thread.

That it does. We get to that later.

You object to me being satisfied with average energy flow
while you satisfy yourself with net energy flow. I don't see
one iota of conceptual difference between our two positions.

They are quite different. I am quite will to explore (and am
doing so) the concept of imputed energy flow in the reflected
wave. It is just that it comes up short since there is no
explanation of where the energy goes. Were an adequate
explanation to be offered, I would quite accept it.

After hundreds of postings, all you have proved is that
Eugene Hecht was right when he said instantaneous powers
are "of limited utility", such that you cannot even tell
me how many joules there are in 100 watts of instantaneous
power when it is the quantity of those very joules that
are required to be conserved and not the 100 watts.

You should tread back through the posts, the question was
answered.

The limit in your quest for tracking instantaneous energy
is knowing the position and momentum of each individual
electron. Good luck on that one.

I am going to summarize the results of my Part 1 article
and be done with it.

In the special case presented in Part 1, there are only
two sources of power dissipation in the entire system,
the load resistor and the source resistor.

Three! The source can also take energy from the system.
Since you have overlooked the source, the rest of your
post is quite flawed in its conclusions.

None of the
reflected energy is dissipated in the load resistor
because the chosen special conditions prohibit reflections
from the source resistor. Therefore, all of the energy not
dissipated in the load resistor is dissipated in the source
resistor because there is no other source of dissipation
in the entire system. Only RL and Rs exist. Pr is not
dissipated in RL. Where is Pr dissipated?

Well that is the question, isn't it? It could be in the source.
Or, if it can not be determined where the energy in Pr goes,
then the only other answer is that Pr does not represent an
energy flow. Think Sherlock: "when the impossible has been
eliminated the residuum, however improbable, must contain the
truth."

Even my ten year
old grandson can solve that problem and he's no future
rocket scientist.

Ah yes, but was he presented with ALL the options?

...Keith