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The electrical magazine
Department of Electrical and Electronics
Volume 1, April 2017

PARAMETRIC MODEL ORDER
REDUCTION
-for a simple mathematical model
Dr. ELIZABETH RITA SAMUEL
ASST.PROFESSOR, DEE
Large scale systems are
present in many fields of
engineering and for
many applications, such
as circuit simulation and
time dependent partial
differential equation
(PDE) control problems,
where the internal
dimension of the system
is quite large, with
respect to the number of
input and output ports. In
suitable for real time
applications.
The challenge in MOR is
t h e a d a p t a t i o n o f
parameter changes. Due
to the high demands on
parameter studies during
geometrical design and
control, the ability to
change parameter values
a f t e r r e d u c t i o n i s
emphasised, especially
d e s i g n p a r a m e t e r s .
Mainly interpolation
based PMOR techniques
have better opportunities
to use various types of
parameters but the
m o d e l s f r o m e a c h
parameter set needs to be
reduced and to which
space they should be
s u b j e c t e d a n d
interpolated is one of the
main focus of research,
these large scale settings,
the system dimension
makes computations
i n t r a c t a b l e d u e t o
memory, time limitations
and ill-conditioning. The
common approach to
overcome this is by
means of model order
reduction (MOR). The
resulting reduced model
can eventually replace
the original system as a
component in a large
simulation or it can be
used to develop a low
dimensional controller
from the fact that a
reduction procedure
requires considerable
amount of calculations.
Therefore in recent
studies, various attempts
to include parametric
effects in the reduced
model are made.
Parametric model order
r e d u c t i o n ( P M O R )
methods are well suited
for such design activities
as they can reduce large
systems of equations
with respect to both
frequency and other
and also one of the
limitation so far is that
only simple models with
a few parameters are
tested.

ELECTRIC SPRING (ES)
-a promising smart grid technology
Ms. PRATHIBHA
ASST.PROFESSOR, DEE
Most PV systems are set
up to disconnect from the
grid whenever they detect
a significant fault. If a
single home’s PV system
trips off-line, it’s
only a headache
for the owner.
But if hundreds
or thousands of
t h e m d o s o
simultaneously, it
could upset the
network’s
delicate balance,
t u r n i n g a n
otherwise small
disturbance into
a n o u t a g e
blacking out an
entire city or county.
Throughout much of the
developed world, electric
utilities are facing an
unprecedented challenge.
Growing numbers of
customers are installing
solar PV systems on their
homes or businesses. The
power they’re injecting
into distribution lines is
causing voltage- and
frequency-control
problems that threaten to
destabilise the grid. While
this is not yet a major
problem, it could become
one as distributed solar
systems proliferate. The
cause of the problem is
the inverter, an electronic
system that converts the
d i r e c t c u r r e n t ( D C )
supplied by the PV panels
i n t o t h e a l t e r n a t i n g
current (AC) that flows
o n t h e p o w e r g r i d .
Although they supply AC
at the right voltage and
frequency to sync with
the distribution grid, they
are otherwise passive.
They can’t sense what is
happening on the grid and
adjust themselves
accordingly. But newer
“smart” inverters can
prevent a PV system from
going off-line when it
doesn’t have to. By doing
so, they can actually make
the grid more stable, by
preventing the sudden
deterioration of voltage
and frequency that would
otherwise occur when
hundreds or thousands of
PV panels are suddenly
taken off-line.
Smart inverters are poised
to fill a big need in the
fast-evolving electricutility
industry. As more
and more homeowners
put PV panels on their
roofs, the power they are
supplying is reducing the
need for big, centralised
generating plants. The
upshot is that increasing
n u m b e r s o f t h e s e
traditional power plants
are getting retired, and
g r i d o p e r a t o r s a r e
scrambling for ways to
keep their networks
running with the same
high level of reliability
that their customers have
long taken for granted.
The combination of smart
inverters and new control
methods will be essential
for helping utilities
transition to the grid of
the future, in which vast
amounts of wind- and
solar-generated electricity
will be the norm. A smart
i n v e r t e r c a n “ r i d e
through” voltage or
frequency dips and other
s h o r t - t e r m g r i d
disturbances and if these
inverters have
communications
capabilities, they can let
grid operators monitor

capabilities, they can let
grid operators monitor
and control them in
response to changing
conditions.
paired, or coupled, their
motions will naturally
align and picture several
weights hanging from
springs that are connected
to a rigid and fixed board.
g r i d f r e q u e n c y w i l l
s i m i l a r l y c a u s e t h e
inverter to adjust its
p o w e r o u t p u t t o
compensate. The use of
“Electric Springs” is a
voltage instability and
frequency deviations. In
recent years, Electric
Springs (ESs) have been
developed as a new
means of addressing these
issues. Besides regulating
a c v o l t a g e s i n t h e
distribution network, ESs
can also regulate the load
power flow to response
the variable renewable
sources. Therefore, it
brings a new control
paradigm, i.e., the load
d e m a n d f o l l o w i n g
v a r i a b l e p o w e r
generation.
The power grids of the
future may need advanced
inverters that don’t simply
follow what the grid is
doing but actually help
f o r m t h e g r i d , b y
r e s p o n d i n g
i n s t a n t a n e o u s l y t o
disturbances and working
in concert to help keep the
g r i d s t a b l e . T h i s
approach, known as
Virtual Oscillator Control
(VOC), was developed by
an NREL team led by
Brian Johnson working
with Sairaj Dhople of the
University of Minnesota;
Francesco Bullo at the
University of California,
S a n t a B a r b a r a ; a n d
Florian Dörfler at ETH
Zurich.
The basic idea behind
VOC is to leverage the
properties of oscillators—
that is, anything that
moves in a periodic
f a s h i o n , s u c h a s a
mechanical spring, a
metronome, or a motor.
When two oscillators are
As the weights are given a
pull to set the springs
bouncing, the springs will
tend to bounce in an
uncoordinated fashion.
However, if the board
itself is suspended from
the ceiling on springs, it
becomes a feedback
mechanism that responds
inversely to the pushes
a n d p u l l s f r o m t h e
bouncing weights. Within
a short period of time, the
weights will all start
bouncing at the same
frequency, all in lockstep.
For virtual oscillator
control, the trick is to
m a k e e a c h i n v e r t e r
respond to the grid much
like a spring: If the grid
voltage drops, the inverter
adjusts its output such
that it “pushes” against
the voltage change.
Likewise, a surge in grid
voltage will induce an
inverter to “pull” the
voltage back to the
n o m i n a l r a n g e . A n
increase or decrease in
novel way of distributed
voltage control while
simultaneously achieving
effective Demand-Side
M a n a g e m e n t ( D S M )
through modulation of
noncritical loads in
r e s p o n s e t o t h e
f l u c t u a t i o n s i n
intermittent renewable
energy sources like Wind,
solar etc. The role of
demand side management
is going to be critical once
t h e p e n e t r a t i o n o f
renewable energy sources
becomes significant. This
would bring about a
paradigm shift from the
traditional centralised
control of hundreds of
power plants to match the
demand to decentralised
control of millions of
loads to balance the
supply (generation). In a
distribution network,
uncertainty and variability
associated with renewable
energy sources, such as
solar power and wind
power, can easily cause
p o w e r f l u c t u a t i o n s ,
An ES connected in series
with the noncritical load
(e.g., a water heater) that
has high voltage variation
tolerance forms the socalled
smart load. The
critical load that requires
a well-regulated mains
voltage is parallel with
the smart load branch. By
operating under inductive
or capacitive mode, the
E S c a n i n j e c t a
controllable voltage and
accordingly change the
uncritical load voltage so
as to maintain the voltage
across the smart load at a
c o n s t a n t l e v e l . I n
addition, it also enables
uncritical load to vary its
power consumption and
thus contributes to the
d e m a n d r e s p o n s e .
Overall, the smart load
c a n b e i n t e n d e d t o
provide reactive power
compensation to the
system by adjusting the
output voltage of ES and
ensure a tightly regulated
voltage across the critical
load.

voltage across the
critical load.
So far, three generations
o f E S s h a v e b e e n
developed. The first
generation, consisting of
a single-phase inverter
w i t h a c a p a c i t o r
installed on the dc-link
side, is connected in
series with a non-critical
load and drawback is its
limited reactive power
c o m p e n s a t i o n
capability. The second
generation is proposed
and it replaces the
capacitor with a battery,
which enables the active
p o w e r r e g u l a t i o n .
However, the battery
brings other problems
such as larger size,
shorter service life and
higher cost. The third
generation solves the
battery problem using
t w o b i d i r e c t i o n a l
inverters connected
back-to-back through a
dc bus, but additional
transformers are
required to isolate the
inverters from the grid.
It is expected that the
ES, as a decentralised
approach, can also be
used to improve the
power quality of the
d i s t r i b u t i o n ( l o w -
voltage) power grids.
Conventionally, single
centralised techniques
such as the series and
s h u n t V A R
compensators are used
at the high voltage level
t o i m p r o v e t h e
performance of AC
p o w e r s y s t e m s b y
p r o v i d i n g 1 ) l o a d
compensation and 2)
voltage support.
There is a growing
interest in using dc
power systems and
micro grids for our
electricity transmission
a n d d i s t r i b u t i o n ,
particularly with the
increasing penetration
of photovoltaic power
systems. ES’s Dispersed
throughout the
distribution system can
provide a strong and
cost effective
m e c h a n i s m f o r
distributed voltage
control that emerged as
a novel way of DSM on
the real time basis.
******
Positive Emotions
and Math
-Learning Reinforce each
other
Positive emotions and success at
learning in math reinforce each
other, according to a new study by
Ludwig-Maximilians University in
Munch on students emotional
attitudes to mathematics.
Research shows that learning and
cognitive performance of students
can b influenced by emotional
reactions to learning, like
enjoyment, anxiety and boredom.
The finding appears in the journal
Child Development.
“ We f o u n d t h a t e m o t i o n s
i n f l u e n c e d s t u d e n t s ’ m a t h
achievement over the years “,
explains Prof. Reinhard Pekrun,
who led the research. “Students
with higher intelligence had better
grades and test scores, but those
who also enjoyed and took pride
i n m a t h h a d e v e n b e t t e r
achievement. Students who
experienced anger , anxiety,
shame, boredom, or-hopelessness
had lower achievement”

INTEGRATION OF SC METHODOLOGIES
WITH SLIDING MODE CONTROL
RING
Ms. RINU ALICE KOSHY,
ASST.PROFESSOR, DEE
Fundamentals of SMC
The SMC theory was originated in late 1950s in the former USSR, led by Prof.
V. I. Utkin and Prof. S. V. Emelyanov [2] to address specific problems associated
with a special class of VSSs, which are the control systems involving
discontinuous control actions.
In the early days of VSS, the research was focused on single-input and singleoutput
systems, and various well-known methodologies were developed, e.g., the
eigen value assignment approach [2], the Fillipov approach [5], etc. In recent
years, the majority of research in SMC has been done with regard to multiinput
and multioutput systems (MIMO), so we will use MIMO system framework as a
platform for discussing the integration of SC methodologies in SMC. Commonly,
the MIMO SMC systems considered are of the form
ẋ˙ = f(x, t) + B(x, t)u + ξ(x, t)
where
x ∈ R n u is the system state vector and ξ(x, t) ∈ Rn represents all the factors
that affect the performance of the control system, such as disturbances and
uncertainties in the parameters of the system.
.It is well known that when this condition (the matching condition) is satisfied,
the celebrated invariance property of SMC stands.
The design procedure of SMC includes two major steps encompassing two main
phases of SMC:
1) Reaching phase: where the system state is driven from any initial state to
reach the switching manifolds (the anticipated sliding modes) in finite time;
2) Sliding-mode phase: where the system is induced into the sliding motion on
the switching manifolds, i.e., the switching manifolds become an attractor. These
two phases correspond to the following two main design steps.
1) Switching manifold selection: A set of switching manifolds are selected with
prescribed desirable dynamical characteristics. Common candidates are linear
hyper-planes.
2) Discontinuous control design: A discontinuous control strategy is formed to
ensure the finite time reachability of the switching manifolds. The controller may
be either local or global, depending upon specific control requirements.
In the context of the system (1), following the main SMC design steps, the
switching manifolds can be denoted as
s(x) = 0 ∈ Rm, where s = (s1, . . . , sm)T

is characterized by the control structure defined by
According to the SMC theory, when the sliding mode occurs, a so-called “equivalent control” is induced,
i.e.,̇
Without loss of generality, we assume that is nonsingular. It is commonly understood that in the sliding
mode, there exists a virtual control signal
which drives the system dynamics resulting in
SMC Design Methods
There are several SMC controller types seen in the literature, which one to use is dependent upon the
specific problems to be dealt with. However, central to the SMC design is the use of the Lyapunov
stability theory, in which the Lyapunov function of the form
is commonly taken. The control design task then becomes to find a suitable discontinuous control such
that V< 0 in the neighborhood of the equilibrium.
If one would like to embed learning and adaptation in SMC to enhance its performance, one common
alternative Lyapunov function may be constructed as
where R and Q are symmetric nonnegative definite matrices of appropriate dimensions.
Typical SMC strategies for MIMO systems include the following.
1) Equivalent control-based SMC. This is a control of the type

and there are other variants.
2) Bang-bang-type SMC: This is a control of direct switching type
should be large enough to suppress all bounded uncertainties and unstructured systems dynamics. Design of
such control relies on the Fillipov method, by which, a sufficient large local attraction region is created to
suck in all system trajectories.
3) Enforce
to realize finite time reachability, where R>0 and K>0 are diagonal matrices and
Key Issues in SMC Theory and Applications
There are several key issues that are commonly seen as obstacles affecting the wide spread applications of
SMC, which have prompted the extensive use of SC and other technologies
in SMC systems in recent years. Some of these are listed in the following.
1) Chattering:
As has been previously mentioned, SMC is a special class of VSSs, in which the sliding modes are induced
by disruptive control forces. As demonstrated in the previous sections, despite the advantages of simplicity
and robustness, SMC generally suffers from the well-known problem, namely,chattering , which is a motion
oscillating around the predefined switching manifold(s). Two causes are commonly conceived.
1. The presence of parasitic dynamics in series with the control systems causes a small-amplitude highfrequency
oscillation. These parasitic dynamics represent the fast actuator and sensor dynamics
which are normally neglected during the control design.
2. The switching non idealities can cause high-frequency oscillations. These may include small time
delays due to sampling [e.g., zero-order hold (ZOH)], and/or execution time required for calculation
of control, and more recently, transmission delays in networked control systems.
Various methods have been proposed to “soften” the chattering. Examples are as follow.
1. The boundary layer control in which the sign function is replaced by which could be a constant or a
function of states as well.
2. The continuous approximation method in which the sign function is replaced by a continuous
approximation Where ε is a small positive number This, in fact, gives rise to a high-gain
control when the states are in the close neighborhood of the switching manifold.
2) Matched and Unmatched Uncertainties:
It is known that the celebrated invariance property of SMC lies in its insensitivity to matched
uncertainties when in the sliding mode. However, if the matching condition is not satisfied, the sliding
mode (motion) is dependent on the uncertainties ξ which is not desirable because the condition
for the well-known robustness of SMC does not hold. Research efforts in this aspect have
been focused on restricting the influence of the uncertainties ξ within a desired bound.

Unmodeled Dynamics:
Mathematically, it is impossible to model a practical system perfectly. There always exists some
unmodeled dynamics. The situation may be worsened if the unmodeled dynamics contains high-frequency
oscillatory dynamics which may be excited by the high-frequency control switching of SMC. There are
several aspects of dealing with this unmodeled dynamics.
More broadly, in the complex systems environment, the object to be controlled is difficult to model without a
significant increase in the dimensions of the problem space. Often, it is more feasible to study the component
subsystems linked through aggregation. The challenge is how to design an effective SMC without knowing
the dynamics of the entire system (apart from the aggregative links and local models). This research topic has
been very popular in recent years in the intelligent control community using, for example, NNs, FL, and
PR,where PR technology is being focused here.
SC TECHNOLOGIES
In this section, some brief introduction to the key SC techniques which are commonly used in dynamical
systems and control. Components of SC technologies are NNs, FL, and PR which subsume belief networks,
evolutionary computation (EC), chaos theory, and parts of learning theory.
PR refers to EC, chaos theory, belief networks, and parts of learning theory. Below are some brief overviews
of the area.
Among PR technologies, EC techniques have been a most widely used technology for optimization in SMC.
The EC paradigm attempts to mimic the evolution processes observed in nature and utilize them for solving a
wide range of optimization problems. EC technologies include genetic algorithms (GAs), genetic
programming, evolutionary algorithms, and strategies. In general, EC performs directed random searches
using mutation and/or crossover operations through evolving populations of solutions with the aim of finding
the best solutions (the fittest survives). The criterion which is expressed in terms of an objective function, is
usually referred to as a fitness function.
INTEGRATION OF SC METHODOLOGIES
The aforementioned SC paradigms offer different advantages. The integration of these paradigms would give
rise to powerful tools for solving difficult practical problems. It should be noted that NNs and EC are about a
process that enables learning and optimization while the FL systems are a representation tool. Emerging
technologies such as swarm optimization, chaos theory, and complex network theory also provide alternative
tools for optimization and for explaining emerging behaviors which are predicted to be widely used in the
future.
SMC WITH SC
There has been extensive research done in using SC technologies for SMC systems. An earlier survey
already out-lined some of the major developments. Since then, significant research has been progressed and
this paper aims to depict the state of the art of SMC with SC. We will use the same categories as in Section
III to summarise the developments.
As has been stated before, the integration of SMC and SC has two dimensions. One is the application of SC
technologies in SMC to make it “smarter” and the other using SMC to enhance SC capabilities. This survey
will be confined within the scope of the former, i.e., the application of SC technologies in SMC.
SMC WITH PR
One PR technology commonly used in SMC is the EC for optimisation. Another area is the application of
chaos theory in SMC. We shall discuss their applications in SMC in the following.

SMC WITH EC:
The optimisation of the control parameters and the model parameters are vitally important in reducing
chattering and improving robustness. In this respect, various optimisation techniques can be used such as
the gradient-based search, Levenberg–Marquart algorithm, etc.; however, a significant amount of
information about the tendency of search parameters toward optima (i.e., the derivative information) is
required. The complexity of the problem and the sheer number of parameters make the application of the
conventional search methods rather hard. The key process of using EC is to treat the set of parameters
(often a large number) as the attributes of an individual in a population and generate enough number of
individuals randomly to ensure a rich diversity of “genes” in the population, through bio inspired
operations such as mutation and/or crossover. The advantages previously mentioned has motivated
various researchers to use EC as an alternative to find “optimal” solutions for SMC.
SMC with Integrated NN, FL, and EC
It is recognised that NNs and EC are processes that enable learning and optimisation while the fuzzy
systems are a representation tool .For complex systems which are difficult to model and represent in an
analytic form, it is certainly advantageous to use fuzzy systems as a paradigm to represent the complex
systems as an aggregated set of simpler models, just like the role of local linearisation plays in nonlinear
function approximation by piecing together locally linearised models. NNs on the other hand can be used
as a learning mechanism to learn the dynamics while the EC approaches can be used to optimise the
representation and learning. Such ideas have been used quite extensively in dynamic systems and control
areas. Research works in this area include two fuzzy NNs are used to learn the control as well as identify
the uncertainties to eliminate chattering in distributed control systems. The conventional BP-based
learning mechanism can be employed for learning.
****

ENERGY STORAGE TECHNOLOGIES &
THEIR ROLE IN RENEWABLE
INTEGRATION
-Dr. UNNIKRISHNAN P.C.
PROFESSOR, DEE
1. S h o r t
Introduction to
the Electric Grid
The amount of electricity
produced must always be
on the same level as
demand. Unfortunately
t h e d e m a n d k e e p s
changing from throughout
the year and through the
day too.(Fig 1)
times and N o toxic
components are its
embedded in a copper
matrix. The Size of the
flow from the renewable
device to the storage
system and
also controls
the flow to
the grid. Fast
r e s p o n s e s ,
capability of
partial and
d e e p
d i s c h a rg e s ,
Fig.1
In addition to this most
renewable energy sources
h a v e a f l u c t u a t i n g
output.So an efficient
storage of energy is
essential. They balance
o u t f l u c t u a t i o n s o f
renewable energies.
1. Energy Storage
Technologies
2.1 Flywheels
Flywheels store energy in
form of kinetic energy in
a rotating hub. Low
maintenance and long
l i f e s p a n , n o c a r b o n
emissions, Fast Response
advantages
a n d i t s
disadvantages
a r e h i g h
acquisition
costs, low
storage
C a p a c i t y
and High
self discharge (2-20 %
per hour)
2.2 Superconducting
M a g n e t i c E n e r g y
Storage (SMES)
A SMES system stores
energy in form of an
electromagnetic field
surrounding the coil.
Fig 3: SMES Components
Most superconducting
coils are wound using
conductors which are
comprised of many fine
filaments of a niobiumtitanium
(NbTi) alloy
Fig. 2
coil depends upon the
Fig. 3
e n e r g y s t o r a g e
requirement and coil
geometry. The power
conditioning system is an
Interface between the
superconducting magnet
and AC power system.
The cryogenic units
maintain a temperature of
about 4.5 K. The control
system controls the power
environmentally safe are
i t s a d v a n t a g e s . T h e
system is very expensive
a n d o f p o o r
efficiency. It also
has high energy
losses ( 12% per
day)
2.3 Batteries
Batteries store
e n e r g y i n
chemical form.
M o s t b a t t e r y
technologies use
t w o d i f f e r e n t
compounds which
release energy in form of
an electrical current when
reacting with each other.
It has high potential for
improvements. The main
drawback is its limited
life cycle and require a lot
o f r e s o u r c e s f o r
production.

2.4 Pumped Storage
Hydroelectricity (PSH)
In a PSH electrical
powered turbines pump
w a t e r i n t o h i g h e r
reservoirs. When needed,
the water flows back
down and power the
reversed turbines. PSH is
capable of storing huge
amounts of energy. High
efficiency, fast response
time and cheap makes it
i d e a l f o r s t o r a g e .
Availability of water is
e s s e n t i a l f o r i t s
operation. Environmental
impacts are of concern.
2.5 Compressed Air
Energy Storage (CAES)
c o m p r e s s e d a i r i n
underground caverns.
The Advanced Adiabatic
(AA) CAES stores the
heat produced during the
c o m p r e s s i o n a n d
compensates the freezing
during the expansion.
T h i s t e c h n o l o g y i s
capable of storing huge
amounts of energy with
high efficiencies. It has
fast response time and
inexpensive too. The
disadvantage is that it is
economical for storage
for a short time.
3 . S u m m a r y /
Conclusion
PSH currently the only
v i a b l e s o l u t i o n ,
Flywheels, SMES and
batteries possess small
potential, CAES shows
the greatest potential.
****
CAES plants store
e n e r g y i n f o r m o f

BROADBAND FOR
TRANSPORTATION -HYPER LOOP
Ms. AISWARYA KRISHNAN
S4 EEE
Conventional means of
transportation (road,
water, air, and rail) tend
to be some mix of
expensive, slow, and
environmentally harmful.
R o a d t r a v e l i s
particularly problematic,
given carbon emissions
and the fluctuating price
of oil. Rail travel is
r e l a t i v e l y e n e r g y
efficient and offers the
most environmentally
friendly option, but is too
slow and expensive to be
m a s s i v e l y a d o p t e d .
Construction
Hyper loop is used for
both passenger and
freight transportation. It
has a pod like vehicle
that will be propelled
through a near vacuum
tube at a speed greater
than the airline speed.
T h e p o d s w o u l d
accelerate to cruising
speed gradually using a
linear electric motor and
eliminating the dangers
of grade crossing.
The Hyper loop was
proposed by Elon Musk,
CEO of SpaceX/Tesla in
a white paper in 2013, as
a replacement to the
California High Speed
Rail.
Theory of operation
Hyperloop has four key
features
1 ) T h e p a s s e n g e r
Given these issues, the
Hyper loop aims to make
a cost-effective, high
speed transportation
s y s t e m f o r u s e a t
moderate distances.
glide above their track
using passive magnetic
levitation or air bearings.
The tubes could go
a b o v e g r o u n d s o n
columns or it could go
underground, therefore
capsules aren't propelled
by air pressure like in
vacuum tubes, but by
two electromagnetic
motors. It is aimed to
travel at a top speed of
760 miles per hour.

2) The tube tracks have a
v a c u u m , b u t n o t
completely free of air.
Instead, they have low
pressure air inside of
them.
power to the periodic
motors.
Advantages of Hyper
loop
Most things moving
through air tubes will
end up compressing the
air in the front thus,
providing a cushion of
air that slows the object
down. But the hyper loop
will feature a compressor
fan in the front of the
capsule. The compressor
fan can redirect air to the
back of the capsule, but
mostly air will be sent to
the air bearings.
3) Air bearings are ski
like paddles that levitate
the capsules above the
surface of the tube to
reduce friction.
4) The tube track is
designed to be immune
t o w e a t h e r a n d
earthquakes. They are
also designed to be selfp
o w e r i n g a n d n o t
obstructive. The pillars
that rise the tube above
the ground have a small
foot-print that can sway
i n t h e c a s e o f a n
earthquake. Each of the
tube sections can move
around flexibly of the
train ships because there
isn't a constant track that
capsules rely on.
And solar panels on the
top the track supply
****

PEROVSKITE EDGES CAN BE TUNED FOR
OPTOELECTRONIC PERFORMANCE - LAYERED 2D
MATERIAL IMPROVES EFFICIENCY FOR SOLAR CELLS
AND LEDS
Ms. ANN CHERIACHEN
THOPPIL
S8 EEE
In the eternal search for
next generation highefficiency
solar cells and
LEDs, scientists at Los
Alamos National
Laboratory and their
partners are creating
innovative 2D layered
hybrid perovskites that
allow greater freedom in
d e s i g n i n g a n d
fabricating efficient
optoelectronic devices.It
m a i n l y i n c l u d e s
Industrial and consumer
applications like low
cost solar cells, LEDs,
laser diodes, detectors,
a n d o t h e r n a n o -
optoelectronic devices.
The material is a layered
compound, a stack of 2D
layers of perovskites
w i t h n a n o m e t e r
thickness (and the 2D
perovskite layers are
separated by thin organic
layers.This work could
o v e r t u r n
conventional wisdom on
the limitations of device
designs based on layered
perovskites."
The 2D, near-singlecrystalline
"Ruddlesden-
Popper" thin films have
a n o u t - o f - p l a n e
orientation so that
u n i n h i b i t e d c h a rg e
transport occurs through
the perovskite layers in
planar devices. At the
edges of the perovskite
layers, the new research
discovered "layer-edgestates,"
which are key to
both high efficiency of
solar cells (>12 percent)
and high fluorescence
efficiency (a few tens of
percent) for LEDs. The
spontaneous conversion
of excitons (bound
electron-hole pairs) to
free carriers via these
layer-edge states appears
t o b e t h e k e y t o
i m p r o v i n g t h e
photovoltaic and lighte
m i t t i n g t h i n - f i l m
layered materials.
Moreover, once carriers
are trapped in these edge
states, they remain
protected and do not lose
their energy via nonradiative
processes.
They can contribute to
p h o t o c u r r e n t i n a
photovoltaic (PV) device
or radiatively recombine
efficiently for lightemission
applications.
"These materials are
q u a n t u m h y b r i d
materials, possessing
physical properties of
b o t h o r g a n i c
semiconductors and
i n o r g a n i c
s e m i c o n d u c t i n g
quantum wells.These
results address a longstanding
problem not
just for the perovskite
family, but relevant to a
large group of materials
where edges and surface
states generally degrade
the optoelectronic
properties, which can
now be chemically
designed and engineered
to achieve efficient flow
of charge and energy
l e a d i n g t o h i g h -
efficiency optoelectronic
devices.
Scientists at Los Alamos National Laboratory and their research
partners are creating innovative 2-D layered hybrid perovskites
that allow greater freedom in designing and fabricating efficient
optoelectronic devices

CAN INDIA BECOME
SUSTAINABLE?
Mr. Jibin George
S8 EEE
J eremy Rifkin, an
economist and activist,
said in New Delhi in
January 2012, “India is
the Saudi Arabia of
r e n e w a b l e e n e r g y
sources and, if properly
u t i l i z e d , I n d i a c a n
realize its place in the
world as a great power”.
Keeping this in our mind
let’s take a glimpse at
t h e p r e s e n t e n e rg y
situation in India.
Dusk descends on a
village in the eastern
Indian state of Bihar as
residents start their
evening chores. Women
walk in a line, balancing
packets of animal fodder
on their heads. Others
lead their water buffalo
home before dinner.
Overhead loom bare
utility poles - built but
n e v e r w i r e d f o r
electricity - casting long
shadows across the
l a n d s c a p e . O f t h e
world’s 1.3 billion
people who live without
access to power, a
quarter (about 300
million) live in rural
India in states such as
B i h a r. N i g h t - t i m e
satellite images of the
sprawling subcontinent
show the story: Vast
swaths of the country
still lie in darkness. It is
quite ironic and It’s a
matter of shame that 68
years after independence
we have not been able to
provide a basic amenity
like electricity to all
citizens.
India, the third-largest
emitter of greenhouses
gases after China and the
United States, has taken
steps to address climate
change in advance of the
global talks in Paris this
year - pledging a steep
increase in renewable
energy by 2030. But
India’s leaders say that
the huge challenge of
e x t e n d i n g e l e c t r i c
service to its citizens
means a hard reality -
that the country must
continue to increase its
fossil fuel consumption,
at least in the near term,
on a path that could
m e a n a t h r e e f o l d
increase in greenhousegas
emissions by 2030,
a c c o r d i n g t o s o m e
estimates.
When Indian Prime
Minister Narendra Modi
talked climate change
with President Obama in
September at the United
Nations, he was careful
to note that he and
O b a m a s h a r e “ a n
u n c o m p r o m i s i n g
commitment on climate
change without affecting
our ability to meet the
development aspirations
of humanity.”. If India’s
c a r b o n e m i s s i o n s
continue to rise, by 2040
it will overtake the
United States as the
world’s second-highest
emitter, behind only
China, according to
e s t i m a t e s b y t h e
International Energy
Agency. Yet the Indian
government has long
argued that the United
S t a t e s a n d o t h e r
industrialized nations
b e a r a g r e a t e r
responsibility for the
cumulative damage to
the environment from
carbon emissions than
developing nations with
Modi urging “climate
justice” and chiding
Western nations to
change their wasteful
ways.
Although 300 million
Indians have no access
to power, millions more
in the country of 1.2
billion people live with

electricity from the
country’s unreliable
power grid. The grid
failed spectacularly in
2012, plunging more
than 600 million people
into total blackout. In
the country’s high-tech
capital of Bangalore, for
example, residents have
recently had to endure
hours of power outages
each day after repairs
and a bad monsoon
season prevented the
state’s hydroelectric and
percent, according to
2 0 11 c e n s u s d a t a .
Families still light their
homes with kerosene
lamps and cook on clay
stoves with cow-dung
patties or kindling.
The Indian government
h a s l a u n c h e d a n
ambitious project to
supply 24-hour power to
its towns and villages by
2022 - with plans for
miles of new feeder
lines, infrastructure
gigawatts of solargenerating
capacity by
2022, plus 75 gigawatts
of other renewable
energy, predominantly
wind. The government
wants to expand its
h y d r o e l e c t r i c a n d
nuclear power capacity
as well. The ambitious
goal - which some see as
unrealistic - would
essentially require the
country to double its
i n s t a l l e d s o l a r -
generating capacity
plentiful coal will make
up the lion’s share of the
country’s energy budget
well beyond 2030. At
the same time, the
Indian government says
it wants to develop its
economy using green
technology, setting up
100 smart cities and
touting its work with
energy efficiency in
industrial buildings and
making LED light bulbs
affordable. In recent
months, the Indian
government
h a s
a n n o u n c e d
p l a n s t o
modernise its
national grid
a n d i s
preparing to
address the
financial
woes of the
country’s
state-owned
u t i l i t y
companies.
wind power plants from
g e n e r a t i n g e n o u g h
e l e c t r i c i t y. E n e rg y
access is worse in rural
areas. Bihar, one of
India’s poorest states,
has a population of 103
million, nearly a third
the size of the United
States. Fewer have
electricity as the primary
source of lighting there
than in any other place
in India, just over 16
upgrades and solar
micro grids for the
remotest areas. Led by
M o d i , a n e a r l y
proponent of solar
technology, India is in
the midst of a huge drive
to expand its solar and
wind capacity, with
plans for dozens of
mega-parks that the
government hopes will
move the country closer
to its goal of 100
every 18 months from its
current capacity of four
gigawatts.
India also wants to
double its coal
production in the next
five years, to more than
1 billion tons annually,
with plans to open 60
more coal mines. India
has the world’s fifthlargest
coal reserves, and
officials say cheap,
India’s
e n e r g y
m i n i s t e r ,
P i y u s h
Goyal, has
b e e n
appealing to wealthier
n a t i o n s t o p r o v i d e
capital to invest in
r e n e w a b l e e n e r g y
projects to help the
c o u n t r y r e a c h a n d
exceed the targets agreed
in Paris in November
2015. Japan’s Softbank
has committed to invest
$20bn (£16.2bn) in the
Indian solar energy
sector, in conjunction

w i t h T a i w a n e s e
company Foxconn and
Indian business group
Bharti Enterprises. In
September the largely
French state-owned
energy company EDF
announced it would
invest $2bn in Indian
r e n e w a b l e e n e r g y
projects, citing the
country’s enormous
projected demand and
“fantastic” potential of
its wind and solar
radiation. Adani opened
the world’s largest solar
plant in Tamil Nadu
earlier this year, and in
October the energy
conglomerate Tata
announced that it would
aim to generate as much
as 40% of its energy
from renewable sources
by 2025.
But even if sufficient
capital is amassed, clean
energy projects will not
be successful without a
resilient power grid.
Solar and wind power is
not as stable as
electricity produced
from conventional
s o u r c e s , h e n c e
upgrading to grids that
are flexible enough to
control unpredictable
surges is a process that
cannot be overlooked.
15-20 percent of the
total renewable energy
generated in the country
is wasted due to the low
capacity of power grids.
Hence, construction of
t h e g r e e n e n e r g y
corridor, a $3.5-billion
project for transmission
of renewable power, is
necessary to offset such
l o s s e s . G e r m a n y ’s
development bank KFW
has agreed to bankroll
$1.1 billion for the
project.
In the 2027 forecasts,
India aims to generate
275 gigawatts of total
renewable energy, in
addition to 72GW of
hydro energy and 15GW
o f n u c l e a r e n e rg y.
Nearly 100GW would
come from “other zero
emission” sources, with
advancements in energy
efficiency expected to
reduce the need for
capacity increases by
40GW over 10 years.
Furthermore, our energy
plan for 2030 involves
generating 850GW of
p o w e r , o f w h i c h
renewables will account
for 40 percent, but the
bulk of the remaining
will come from coal as it
continues to be the
cheaper option. But
since the present
government is headed in
the right direction and is
committed to walking
the renewables path, we
could step up our game
t o r e a c h o u r f u l l
renewable potential.
‘Overlearning’ -
Locks in Performance
Gains
A new Brown University study
suggest that you should keep
practicing for a little while after
your think you can’t get any better.
Such overwhelming locked in
performance gains according to the
nature neuroscience paper that
describes the effect and its
underlying neurophysiology.
Learning has to sink in the brain.
Overwhelming cements learning
well and quickly suggests the study.
“If you want learn something
important, may be over learning is a
good way”, suggests the research.
“If you do overlearning,you may be
able to increase the chance that what
you learn will not be gone.

FIREFLY LEDS
Mr. Rony Joseph
S8 EEE
The nighttime twinkling
of fireflies has inspired
scientists to modify a
light-emitting diode
(LED) so it is more than
one and a half times as
efficient as the original.
Researchers from
Belgium, France, and
Canada studied the
internal structure of
firefly lanterns, the
organs on the
bioluminescent
i n s e c t s ’
abdomens that
flash to attract
m a t e s . T h e
scientists
identified an
u n e x p e c t e d
p a t t e r n o f
j a g g e d s c a l e s t h a t
enhanced the lanterns’
glow, and applied that
k n o w l e d g e t o L E D
design to create an LED
overlayer that mimicked
the natural structure. The
o v e r l a y e r , w h i c h
increased LED light
extraction by up to 55
percent, could be easily
tailored to existing diode
designs to help humans
light up the night while
using less energy.
Fireflies create light
through a chemical
reaction that takes place
in specialized cells called
photocytes. The light is
emitted through a part of
the insect’s exoskeleton
called the cuticle. Light
travels through the
cuticle more slowly than
it travels through air, and
the mismatch means a
proportion of the light is
reflected back into the
lantern, dimming the
glow. The unique surface
g e o m e t r y o f s o m e
f i r e f l i e s ’ c u t i c l e s ,
h o w e v e r, c a n h e l p
minimize internal
reflections, meaning
more light escapes to
r e a c h t h e e y e s o f
potential firefly suitors.
Using scanning electron
m i c r o s c o p e s , t h e
researchers identified
s t r u c t u r e s s u c h a s
nanoscale ribs and larger,
misfit scales, on the
fireflies’ cuticles. When
the researchers used
computer simulations to
model how the structures
a f f e c t e d l i g h t
transmission they found
that the sharp edges of
the jagged, misfit scales
let out the most light. The
finding was confirmed
experimentally when the
researchers observed the
e d g e s g l o w i n g t h e
brightest when the cuticle
was illuminated from
below.
“The tips of the scales
protrude and have a tilted
slope, like a factory
roof.” The protrusions
repeat approximately
every 10 micrometers,
w i t h a h e i g h t o f
a p p r o x i m a t e l y 3
micrometers. “In the
beginning we thought
smaller nanoscale
structures would be
most important, but
surprisingly in the end
we found the structure
that was the most
effective in improving
light extraction was
this big-scale
structure,” say the
researchers.
The firefly specimens
t h a t s e r v e d a s t h e
i n s p i r a t i o n f o r t h e
effective new LED
coating came from the
genus Photuris, which is
commonly found in Latin
America and the United
S t a t e s .
“The Photuris fireflies
are very effective light
emitters, but we are quite
sure that there are other
species that are even
more effective,” says the
researchers and will
continue to explore the
great diversity of the
natural world, searching
for new sources of
k n o w l e d g e a n d
inspiration.

THE INTERNET OF ENERGY
Mr. KADAVIL SABU
HAZEM
S8 EEE
We waste too much
energy and this is a
direct cause of global
warming. Imagine a
f u l l y i n t e g r a t e d
electrical system that is
s a f e r, c l e a n e r a n d
s u s t a i n a b l e . B y
utilising the Internet,
Smart devices, sensors
and switches
technologists have
designed systems that
s a v e e n e r g y i n a n
intelligent fashion,
saving the consumer
money in the process.
devices include sensors,
Smart devices, lights,
motors and vehicles as
well as any compatible
e l e c t r o n i c s . T h e
advantages of such a
system are increases in
automation, accuracy,
efficiency and experience
quality; going beyond
current “machine:
machine” systems. It is
estimated that the IOT
will contain over 50
billion objects by 2020.
The Internet of
Energy
software and middleware
for seamless, secure
c o n n e c t i v i t y a n d
interoperability achieved
b y c o n n e c t i n g t h e
Internet with the energy
g r i d s . T h e
implementation of IoE
services involves the use
of multiple components,
including embedded
s y s t e m s , p o w e r
electronics or sensors;
which are an essential
part of the infrastructure
d e d i c a t e d t o t h e
g e n e r a t i o n a n d
distribution energy.
The Smart Grid
Large territories have
developed interconnected
electrical supply systems
that use the same
voltages and currents;
these are most evident in
large countries/continents
like USA, Brazil and the
EU where the electrical
grids are standardised.
The Internet of
Things
Sometimes the simplest
ideas are the best: The
Internet of Things uses
the existing infrastructure
of the Internet to allow
devices to communicate
and share data. These
As a subset of the IOT,
the Internet of Energy
(IOE) encompasses all
objects involved in
provision and use of
electricity from the
power grid down to
individual electronic
devices. The main
objective of the IOE is to
d e v e l o p h a r d w a r e ,
The IOE makes use of
millions of sensors across
the grid (devices, sockets
etc.) and integrated
computing systems,
connected using existing
Internet infrastructure,
allowing the prediction
o f f u t u r e e n e r g y
requirements: The Smart
Grid. This affords huge
savings in the amount of
energy usage, in the form
of fossil fuels and
others. Encouragingly
there are currently over
500 Smart Grid projects

throughout the EU.
Smart Energy Devices
Smart socket devices on
the market offer basic
functionality that trails
behind what has been
achieved in the lab;
available devices can
turn off appliances, run
schedules and monitor
consumption but they are
not fully automated i.e.
they do not respond
intelligently to real time
changes.
The importance of Smart
devices in the IOE
cannot be underestimated
and researchers at The
University of Coruña
have recently presented a
system that monitors
electrical usage in the
home and optimises
consumption according
to user preferences and
electricity prices.
Researchers have a
produced an integrated
system that uses live
e l e c t r i c i t y p r i c e s ,
o b t a i n e d f r o m t h e
Internet, in order to
optimise usage for the
user. This system also
self-organises, using the
Wi-Fi infrastructure so
that it can collect data
w i t h m i n i m a l u s e r
intervention. All of the
software is open source,
allowing its modification
by future developers and
uses.
The System
Sensor and actuation
subsystem: This controls
the sensors and actuators
o f t h e s y s t e m ;
responsible for collecting
current data and for
activating the power
outlet when it receives a
request from the control
subsystem.
Communications
subsystem: This consists
of wireless transceivers
t h a t j o i n a n a u t o -
c o n f i g u r a b l e s t a r
topology.
M a n a g e m e n t
subsystem: This provides
t h e u s e r w i t h t h e
possibility of obtaining
the current status of all
modules, modifying their
configuration and acting
d i r e c t l y o n t h e m
remotely through a web
interface.
Control subsystem: This
oversees controlling and
managing the remaining
subsystems, processing
the data through the
appropriate algorithms
and acts as the gateway
of the network to connect
to the Internet.
The Future of the
IOE
I t h a s b e e n
demonstrated that this
system can be used to
o p e r a t e d e v i c e s a t
optimum times, saving
energy and money (up to
70€ / year /device) by
using online energy
prices. It could also be
optimised according to
energy availability; for
example, washing
machines would be used
at midday, when the
electricity generated from
solar panels is at a
maximum. Smart
sockets, thermostats and
motion detectors are well
established technologies
that are integrated into
t h e I O E i n S m a r t
Houses; these monitor
all energy used by the
home and data can be
analysed / modelled for
specific streets or areas.
The Internet of Energy
will ultimately provide a
beautifully integrated
system that monitors and
predicts consumption
patterns. Eventually
systems like the one
presented here will exist
i n a l l h o m e s a n d
f e e d b a c k d a t a t h a t
o p t i m i s e s p o w e r
generation. This system
will offer high levels of
participation to the user;
p l u g a n d p l a y
convenience for new
devices; faster response
to power outages and
faults; and resilience to
a t t a c k a n d n a t u r a l
disasters. The IOE can
operate on a small scale,
saving the user money in
the home; as well on the
grid scale, allowing more
efficient electricity
g e n e r a t i o n a n d
decreasing fossil fuel
usage.

CARBON NANOTUBES AND ITS
FUTURE IN TAPPING SOLAR ENERGY
Mr.SIDHARTH R.S.
S8 EEE
We waste too much With
the increasing concern
about the carbon dioxide
concentration and global
warming in the earth, as
well as the increasing
demand on energy and
the limitation of fossil
f u e l s r e s o u r c e s ,
researches have been
addressed towards other
energy alternatives such
a s t h e a m a z i n g
sustainable source of
energy, the sun. It has
been calculated that less
than one hour of sun
energy received by the
earth is enough to satisfy
the annual world human
demand of energy. The
solar energy is clean,
abundant and without
any harmful effects on
the environment. The
photovoltaic effect is the
process allowing the
conversion of light into
electricity, this process
needs semiconductors
materials in order to
convert the photons into
e l e c t r o n s . T h e
photovoltaic solar cell
technology with its
different generations is a
multidisciplinary field
i n v o l v i n g c l a s s i c a l
disciplines like physics,
chemistry and materials
sciences, beside new
emerging technologies
such as optoelectronics,
organic electronics and
nano electronics. These
technologies have been
tremendously expanded
in the last decades,
serving the development
of photovoltaic solar
cells and making the
field rich and attracting
f o r s e v e r a l f a m o u s
worldwide universities,
institutes and research
centres.
A solar cell (photovoltaic
cell) is a solid state
electrical device that
converts the energy of
l i g h t d i r e c t l y t o
e l e c t r i c i t y b y
photovoltaic effect. The
solar cells of today are
typically made of silicon,
a n i n o r g a n i c
semiconductor material
k n o w n b y i t s
environmental stability,
high purity and its
distinguished charge
transport properties. The
silicon solar cells are
d o m i n a t i n g t h e
Photovoltaic market
thanks to their high
p o w e r c o n v e r s i o n
efficiency which hits
25% as per the latest
report. In spite of its
market dominance and
high conversion rates,
fabrication of silicon
s o l a r c e l l s i s
complicated, expensive
and energy-intensive
leading to a costly
manufacturing. The lack
of a cost-effective energy
in the inorganic solar cell
technology has been one
of the major drawbacks
t h a t i n c r e a s e d
i n v e s t i g a t i o n s o n
a l t e r n a t i v e s a n d
promoted organic solar
cells researches. An
organic solar cell or
plastic solar cell is a type
of photovoltaic that uses
organic electronics, a
branch of electronics that
deals with conductive
organic polymers or
small organic molecules,
for light absorption and
charge transport to
produce electricity from
s u n l i g h t b y t h e
photovoltaic effect. The
o r g a n i c s o l a r c e l l
technology is now a
d a y s , a p r o m i s i n g
competitive alternative of
the inorganic solar cell
technology, specifically
in terms of fabrication
simplicity, cost and also
its ability to bend allows
it to be used in areas
where inorganic solar
cells can’t be used.While
working on organic cells,
researchers were struck
with a basic theory. If
organics involve the use
o f c a r b o n a n d i t s

allotropes, why not use
carbon in solar cells?
This is how carbon
nanotubes (a special form
of carbon) came to be
considered for tapping
solar energy.
Before studying about
carbon nanotubes, we
need to know what
n a n o t u b e s a r e .
Nanotubes are particles
that are on the nanoscale,
which is are about 1 to
100 nanometres (nm) in
size. For comparison, the
thickness of a sheet of
paper is about 100,000
nm and the width of a
hair, about 40,000 –
80,000 nm. Materials that
exhibit a dimension
below 100 nm have very
different and interesting
properties than the bulk
material. As an example,
gold is a very inert metal,
but below 100 nm,
nanoparticles of gold
possess properties that
m a k e t h e m g o o d
catalysts and sensors.
With this in mind, let us
s e e w h a t c a r b o n
nanotubes are. Carbon
nanotubes (CNTs) are
allotropes of carbon with
a c y l i n d r i c a l
nanostructure. These
c y l i n d r i c a l c a r b o n
molecules have unusual
properties, which are
v a l u a b l e f o r
n a n o t e c h n o l o g y ,
electronics, optics and
other fields of materials
science and technology.
So, Why use CNTs in
Solar Cells?
Any solar cell should
have good photovoltaic
properties to provide
maximum number of
electron-hole pairs for a
g i v e n i n t e n s i t y o f
incident light. The cell
should be as strong as
possible to improve its
life and should work at
maximum possible
efficiency. Above all, it
should be cheap. Well,
CNTs have many such
desirable properties that
make it a potential
photovoltaic material in
the coming years. When
light falls on a solar cell,
electrons are generated
and transferred to the
external circuit via
metallic conductors and
connectors. If the photoreception
part of the cell
contains CNTs, a lot of
positive differences can
be observed. This is due
t o t h e e l e c t r i c a l
properties of CNTs. They
are hollow cylinders and
hence electrons can only
flow over its surface
c o m p a r e d t o t h e
conventional wires. Due
to this reason, CNTs
offers lesser resistance to
the flow of current and
can help reduce losses.
As for light harvesting
p r o p e r t i e s , c a r b o n
nanotubes possess a wide
range of direct bandgaps
m a t c h i n g t h e s o l a r
spectrum and its strong
photoabsorption from
infrared to ultraviolet,
allows it to absorb light
belonging to different
f r e q u e n c i e s a n d
wavelength. It has high
carrier mobility and
reduced carrier transport
scattering which allows
C N T s t o t r a n s f e r
maximum current to the
external load as much as
possible with minimum
loss of electrons within
the bulk of the cell. What
good can a solar cell do
if it can’t protect itself
from mechanical
s t r e s s e s ? C a r b o n
nanotubes are the
strongest and stiffest
materials yet discovered
in terms of tensile
strength and elastic
modulus respectively.
Recently, SWNTs were
directly configured as
e n e r g y c o n v e r s i o n
materials to fabricate
thin-film solar cells, with
nanotubes serving as
both photogeneration
sites and a charge carriers
collecting/transport layer.
The solar cells consist of
a semitransparent thin
f i l m o f n a n o t u b e s
conformally coated on an
n-type crystalline silicon
substrate to create highd
e n s i t y
p - n
heterojunctions between
nanotubes and n-Si to
favor charge separation
and extract electrons
(through n-Si) and holes
(through nanotubes).
Initial tests have shown a
p o w e r c o n v e r s i o n
efficiency of >1\%,
proving that CNTs-on-Si
is a potentially suitable
configuration for making
solar cells. For the first
t i m e , Z h o n g r u i L i
demonstrated that SOCl2
treatment of SWNT
b o o s t s t h e p o w e r
conversion efficiency of
S W N T / n - S i
heterojunction solar cells
by more than 60%. Later
on the acid doping
a p p r o a c h i s w i d e l y
adopted in the later
published CNT/Si works.
Even higher efficiency
can be achieved if acid
liquid is kept inside the
void space of nanotube
network. Acid infiltration
of nanotube networks
significantly boosts the
cell efficiency to 13.8%,
as reported by Yi Jia, by
reducing the internal
resistance that improves
f i l l f a c t o r, a n d b y
f o r m i n g
photoelectrochemical
units that enhance charge
separation and transport.
The wet acid induced
problems can be avoided
by using aligned CNT

film. In aligned CNT
f i l m , t h e t r a n s p o r t
distance is shortened, and
the exciton quenching
rate is also reduced.
Additionally aligned
nanotube film has much
smaller void space, and
b e t t e r c o n t a c t w i t h
substrate. So, plus strong
a c i d d o p i n g , u s i n g
aligned single wall
carbon nanotube film can
further improve power
conversion efficiency (a
r e c o r d - h i g h p o w e r-
conversion-efficiency of
>11\% was achieved by
Yeonwoong Jung).
***
ARTIFICIAL LEAF: SOLAR CELL
THAT PRODUCES HYDROCARBON
M r. H . R AV I S A N KA R
MENON
S8 EEE
Researchers have
developed a new type of
solar cell that is capable
of transforming carbon
dioxide into usable
hydrocarbon fuel using
only sunlight as energy.
C o m p a r e d w i t h
conventional solar cells
that convert sunlight into
electricity to be stored in
batteries, the new solar
c e l l s c h e a p l y a n d
efficiently convert carbon
d i o x i d e i n t h e
atmosphere directly into
usable fuel.
The new device works
much like trees and
plants that capture and
convert carbon dioxide
into sugars to store them
into energy. Unlike plants
that use catalysts to
p r o d u c e s u g a r, t h e
r e s e a r c h e r s u s e d
n a n o f l a k e t u n g s t e n
diselenide catalyst to
convert carbon dioxide to
carbon monoxide.
o f o t h e r k i n d s o f
hydrocarbons such as oil,
gasoline and coal.
A solar farm of these soc
a l l e d a r t i f i c i a l
leaves can also remove
significant amounts of
the greenhouse gas
carbon dioxide in the
atmosphere known to
significantly drive global
warming.
In plants, the process of
c o n v e r t i n g c a r b o n
d i o x i d e i n t o s u g a r
involves the organic
catalyst enzyme. Carbon
monoxide is also a
p l a n e t - w a r m i n g
greenhouse gas but
scientists have already
found a way to convert it
into usable fuel such as
methanol. Converting
carbon dioxide into
something usable, on the
other hand, is more
challenging because of it
b e i n g r e l a t i v e l y
chemically unreactive.
packets of light, into
p a i r s o f n e g a t i v e l y
charged electrons and
positively charged holes
that separate from each
other. When the holes
r e a c t w i t h w a t e r
molecules, protons and
oxygen molecules are
created. Along with
carbon dioxide, the
protons and electrons
then react together to
p r o d u c e c a r b o n
monoxide and water.
***
The new solar cells
produce usable energydense
fuel, which could
help address challenges
linked with the burning
The system involves a
reaction very much
similar to that found in
nature. The artificial leaf
converts photons, or

Answers:
1. Differential 2. Inductor 3. Nitrogen 4. Lightning 5. Neutral 6. Tesla 7. Clampmeter
8. Buchholz 9. Zener 10. Magnet 11. Governor 12. Delta 13. ELCB 14. CDMA
1 2 3 4
5
7 12
6
8
10 11
13 14
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1.Internal Fault Detection Of Transformer
2.What Blocks AC
3.Gas Filled In Transformer Conservation Bladder
4.Rolling Sphere method Is Used For Which Protection Design
5.Formed From R,Y And B Phases
6.The Standard Unit Of Magnetic Flux Density
7.An Electrical Test Tool That Combines A Basic Digital Multimeter With A Current Sensor
8.A Safety Relay Device Mounted On Oil Filled Power Transformers
9.A Form Of Semiconductor Diode
10.This Is Required To Produce Electricity
11.A Device Used To Measure And Regulate The Speed Of A Machine
12.A Type Of Transformer Winding Connection
13.A Safety Device Used In Electrical Installations With High Earth Impedance To Prevent
Shock
14.A Digital Cellular Technology That Uses Spread Spectrum Techniques