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REVIEW PAPERS
DECISION FACTORS IN THE SELECTION OF ELEVATOR
By
VISHAL V. SHUKLA * PRAVIN P. TAMBE **
*-** Associate Professor, Shri Ramdeobaba College of Engineering and Management (RCOEM) Nagpur, India.
ABSTRACT
Decision to install and commission a modern lift or an elevator in institutional, commercial or residential building has
been considered to be a challenging task. The project assignment does not only involve a multidisciplinary expertise, but
also requires permissions and approvals from various government and private authorities like Municipal Corporation,
Public Works Department (PWD), Architect, Structural Engineer etc. Despite the vast, wide spread of the intricacies of the
topic, this article intends to provide the readers with some general and a few detailed important factors while making
decisions towards lift installations. Numerous options of elevators are available in the market with different qualities and
costs which make the selection process a difficult task. Selecting a lift signifies to be a Multi-criteria Decision Making
(MCDM) problem and it is illustrated that decision can be effectively addressed by Analytical Hierarchy Process (AHP).
The article intends to present some useful tips that can be adopted while installing the elevators to the technical
decision makers.
Keywords: Machine Room Less (MRL), Gearless, Elevators.
Date Received: Date Revised: Date Accepted:
INTRODUCTION
Vertical transport systems, also called as Lifts or Elevators,
are essential for easy and comfortable movement of
people or goods from floor to floor in tall and high rise
buildings. The necessity of handling of material or
movement of object, typically at challenging highrise sites
and at difficult terrains had initiated developments of
elevators. Steel beam constructions are extensively used in
the passenger and freight elevators today. The installation
of lift involves huge cost of mechanical components,
electrical machines and cables, civil structures etc. Lifts
were invented as simple rope or chain hoist systems.
Higher capacity elevators usually operates automatically
through touch controls, whereas a lift operates on pressure
selected through button. Worldwide, an elevator is mostly a
synonym for lift. Lifts are designed to transport only one
person, while elevators are designed to transport a person
or goods. Simply, elevators lift humans or objects to desired
vertical distance. It's a room like structure but elevator is
sometimes used for under construction buildings etc.
Simple elevator elevates materials, machines, people etc.
Elevators are also sometimes a electrical stair case which
moves up itself.
Elevators were developed for movement of raw materials
on hillsides. The material handling technology based on
construction of rails, ropes, steel beam etc. is then
eventually evolved for the movement of the passenger.
Steam power operated elevat ors were extens ively
employed in mines and factories.
During the next stage of development, hydraulic systems
with oil pressure, pressure to raise and lower the elevator car
became popular in residential and office premises (Celik
and Korbahti 2006). However, one of the disadvantages of
hydraulic elevators was need of a pit below the lift shaft for
piston movement. Moreover, for higher travels of a cabin
car would require larger piston and larger stroke, resulting in
bulky powerpack. Therefore, researchers and designers
had to focus on a viable option for multistoreyed buildings
with improved safety, compactness and robustness.
Hence, despite the hydraulic systems being popular for
about half a millennium, problems related to oil leakages,
cable damages leading plummeting of cars to bottom,
bulkiness of hydraulic power packs, oil coolers, counter
wirghts, damage to structure of building etc., laid a
foundation for altogether a new generation of electrical
elevators.
42
1. Materials and Methods
A cabinet enslosure carrying live stock load or passengers
that are manuevered up and down over a vertical guide
rails in a shaft or hoist way by mechanical means are
referred as lifts. Since its inception 100 years back, the
technology has witnessed mechanical, hydraulic and
electrically operated elevators with gradually increasing
robustness, reliability, comfort and safety. Earlier, lift drive
mechanisms were powered by steam and water hydraulic
pistons or by hand. Modern elevators are a beautiful
conglomeration of multidisciplinary engineering fields
involving civil, mechanical, electrical and electronics
systems.
Stee l ropes m oving o ver gro oved pulle ys prov ide
necessary friction-traction required for motion of cabin car
against th e cou nte r w eig ht. Sy nch ronizing two l ift s
simultaneously moving in opposite directions can act as
complimentar y co un te rweights to each other and
therefore are considered to be much more economical.
Use of hydraulic lifts are commonly found in limited to low to
mid-rise buildings. Ropes and hydraulic power provide
engineering suitability to raise and lower the lift cars.
Installation of lengthy hydraulic cylinders for a multistoreyd
high rise building becomes tedious and sometimes
impractical. The latest amongst the elevator technologies
essentially incorporates smooth gearless microprocessor
controlled magnetic drive motors, directly installed over
the lift car itself. The complete assembly moves with the car
and therefore does not require a separate machine room.
Space requirement is one of the influential factors in new lift
installations in high rise buildings. Every building comes with
its own varied requirements like age of the building,
number of floors, dimensions of the well and usage
patterns. Therefore, required customization can sometimes
affect the economics of lift installation contract.
2. Observations and Discussion
While making the decision to install a lift, the first and
foremost important part to be considered is building
regulation which includes authentic floor wise architectural
drawing containing elevation, building plan showing lift
shaft and also approved by competent authority like
Mu nic ipal C orp oration, Cer tif icat e fro m S tru ctural
engineering consultant.
The second part focuses on technical specifications which
includes Capacity, Speed (mps), STOPS, Drive Power Supply,
Operation, Rescue, Machine Traction Media, Car Finish,
Car door and landing door frame, Hand Rails, Ventilation,
Floo ring, Car f ittings, Fire Rating D oors, Hoist w ay
Dimensions, Door Operator, Care Operating Panel, Car
Position Indicator, Power, Brakes, Emergency Services,
Emergency Car Light Unit, Door Screen, Door Time
Protection, Emergency Alarm Bell, Extra Door Time of Lobby
and Parking, Door Open/Close Button, Maintenance
Service/Guarantee Warranty, Civil Work inside Shaft etc.
The third part is about finance and accounts like taxes,
fr e i ght, p a cka g i ng, t ran s p ort, d e li v e r y p e r iod ,
commissioning and annual maintenance contract.
The fourth and the last part is to release Purchase-cum-Work
Order and part payments if necessary as per P.O.
whereupon the man ufacturer su bmits th e General
Arrangement Drawing (GAD). GAD shows the proposed
arrangement of the lift equipment in the lift well, pit and
entrance areas, including the overall sizes and weights of
all major items of lift equipment. It also indicates the
magnitude, position and direction of all loads imposed on
the building structure by the lift and its associated
equipment on the general arrangement drawings. The
verified and approved GAD by the customer then needs to
be resubmitted to the manufacturer for forwarding to the
material estimates and the licensing authority such as PWD
In s p ector. Ma t e rial pro c u remen t an d t h e a c tual
installation, erection and commissioning are followed by
inspection, testing and licensing by the PWD Lift Inspector.
The lift manufacturer and supplier is responsible for ensuring
th e s e l ected equ i p ment meet i n g t h e f unctio n a l
requirements as indicated within the documentation, and
including for all the features included in this specification.
The equipment specified for the installation should include
the following factors:
·Suitability of equipment
·Reliability of equipment
·Vandal resistance
·Maintenance aspects
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·Energy efficiency
·Capital costs
·Running costs
·Plant and equipment 'life' spans
In addition to the traffic analysis, available lift shaft size is the
main criterion that decides the capacity of lift in terms of
weight to be hoisted. This is specifically indicated in terms of
the number of persons that can be accommodated in the
lift car. Modern lifts are typically suitable for a shaft size 1.8
m X 1.9 m or bigger than that and can carry 10 persons
weighing 680 Kg. This lift is shaft size and capacity are bare
minimum wherein a modern elevator with best suitable
configuration can be fitted. Rated load and size of the car
should be practicable, the same as the existing lift cars;
where the car size can be increased, this should be
considered.
The major strength parameters in the modern lifts that
make them up to date are Machine Room Less (MRL),
gearless, central opening and sliding auto-door, coated
flat belts as traction media, Microprocessor based Variable
Voltage and Variable Frequency (VVVF) with AC motor
driv es for Je rk free ride, Protectio n Again st Pow er
Fluctuations (PAPF), Manual as well as Automatic Rescue
Device (ARD), travel speed range from 1.02 mps to 1.78
mps, auto dialer, Intercom system for car cabin, Closed
Circuit Television (CCTV) camera, car top and lift pit and
most of the parts made in good quality stainless steel.
Some of the modern lift units are also equipped with
regeneration type, which sends back the unused power or
the power that is generated during travel, back to the main
grid. This technology is expected to replace the older
ve rsi ons soo n. Th e othe r feat ured a cces sor ies of
decorative, aesthetics and elegance look including
vandal proof car operating panel, mirror, ceiling, flooring,
Light- E m i t t i n g Diodes (L E D s ) , v e n t i l a t i on and air
conditioning etc., further adds value to vertical travel
experience.
2.1 Types of Elevators
2.1.1 Hydraulic Elevators
·In ground
·Twin jack holeless
·Twin Jack Telescopic Holeless
·Roped
·Holeless MRL
·Freight
2.1.2 Traction
·Machine Room Less (MRL)
·Freight
·Geared
·Gearless
There could also be specific requirements of elevators
based on needs of application or field like vertical transport
of grains, food (dumb elevators), radio antennas, bridge
towers, open cast or closed underground mines, dams
and power plants where only Special Purpose Elevators
(SPE) can be implemented.
2.2 Machine Room Less (MRL) Lift
MRL elevators are a type of traction elevators. They do not
require a machine room on the top of the hoist way (Tetlow,
2007). Therefore about 120 Sq. ft. space is saved. MRL
consists of a magnet, permanently fixed to a synchronous
motor which functions with 3VF drive, thereby reducing
otherwise required considerable space for conventional
motor. Figure 1 shows the block diagram for V3F drive. The
traction hoisting machine is placed on the top side wall or
the bottom of hoist way. Hence the main controller (230 V
AC) is placed on the top or bottom floor (bottom drive
elevators – popular in japan) next to the landing doors
behind the locked cabin with or without keys for ease of
ma i nten a nce, r epair s a n d e merg e ncy purp oses.
Aesthetically, pleasing and without key are preferred.
Some MRL elevators have controller cabinet installed within
the door frame to save space, however they are very rare.
Electrical equipments are protected from direct contact
with shrouded terminals. A direct acoustic communication
system between the control panel and the lift car is usually
provided in the modern MRL lifts. MRL elevators are
normally incorporated into new building design with low-
rise (4-4 floors) to mid-rise (20 floors).
Modern MRL incorporates gearless, Permanent Magnet
Sync hro nou s (PMS) moto rs re placing conve nti onal
induction motors. The design of modern gearless MRL
RE VI EW PA PE RS
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elevators eliminates machine room requirement and
therefore saves substantial building space. Gearless MRL
technology can be used for both front and, front and rear
open elevator cars. The assembly of gearless machines
comprises a drive motor, drive sheave, bedplate, brake
rotor, supporting bearings and a deflector or double wrap
sheave. The assemblies are super silent in their operation
and insulated from the building fabric to ensure no noise or
vibration pollution affecting the people nearby.
Gearless MRL eliminates the necessity of gearbox thereby
saving a lot of space and weight. Gearless PMS AC motor is
the most power efficient, particularly when installed with the
regeneration inverter unit. The gearless drive system uses
40% less energy than the traditional geared lift. This means
savings of a few thousand kWh/year for a single lift. The PMS
gearless MRL drive technology powered by a 3VF inverter
unit directly connected to sheave, controls the necessary
torque throughout the full speed range of the elevator.
There are instances during operation of elevator wherein a
small amount of power is generated by the elevator system
itself e.g. during lowering of the cabin car or applying
electrical brakes or retarding stages before coming to rest
at very landing. The smart microcontroller diverts this power
to storage device, this cirucuitary arrangement called
regen unit receives excess power and may either utilize for
elevator or send to power grid. Loaded elevators descend
faster due to gravity. In this case, instead of consuming the
power, motor delivers rather generates the power, which in
turn could be used for other domestic application. On the
other hand, in conventional drive systems the heat
generated during operation calls for dissipation by means
of air conditioning system. The PMS with regeneration
Figure 1. Block Diagram for V3F Drive
RE VI EW PA PE RS
45
facilitates bidirectional energy flow.
Harvesting regenerative power is an effective approach for
gearless MRL to enhance their efficiency. It is the emerging
technology used on electric or hybrid transport systems to
recoup some of th e energ y lost during stop ping.
Regenerative energy has to be injected in conventional
power source. In gearless V3F MRL design for vertical
transport systems, when the elevator speed is reduced,
directional stability is controlled through governor and a
microprocessor based control system. The regenerated
energy is saved in a storage battery and used later to
power the motor. Regenerative system takes energy
wasted during operation or in braking, and turns it into
usable energy (Balaji et al., 2011). It improves energy
efficiency of the lift. The electricity generated during
operation or braking varies according to the speed of the
lift. So to utilize the generated electricity completely, a
suitable Electronic Control Unit is necessar y.
Drive systems in most of the modern elevators offer the
regeneration option. Regeneration unit (regen) is an
excellent option; firstly in extensively travelling busy
elevators and secondly, for that, it utilizes the power
produced by the lift itself by conserving energy. This would
be one of the most favored features specifically when the
world eyes for efficient and effective systems in energy
har vesting and optimum utilization. The regen unit
contributes significantly for saving the electrical power
during running of a lift. However, a power requirement for
gearless MRLs in standby mode is little higher compared to
power requirements of hydraulic elevator drives or
electrical. Gearless MRLs other wise when operational
consumes much lesser power and proves to be more
beneficial and economical. To eliminate these demerits,
researchers and design engineers are working to develop
hybrid systems incorporating partial power supply from
solar systems as well.
Addition all y, sp ace, bu ild ing m ate rial and he nce
construction time required in installing MRL is less since it
requires no separate machine room. Also, space for
headroom and pit is saved considerably. By locating all the
lift equipment in the shaft, it offers architects and designers
the freedom to design without a machine room, hence
freeing up valuable space inside the building for more
produ cti ve use. Moreo ver, the co mpa ct gearle ss
machine, a larger car for carrying more number of
passengers (or weight) can be fitted into a standard shaft
space.
The motor has two separate electric brakes equipped with
a mechanical hand release and monitoring switches. A
tacho-generator is also built into the machine assembly.
The brakes of modern MRL are able to stop the lift at 125%
of designing load. Travelling Contractors, brake resistances,
EMC filters and motor reactors are integrated into the
compactly designed inverter.
Modern MRL also consists of flexible, high strength belts
which saves much space and allow to incorporate the
minimum size of hoisting sheave. These belts are about
30% lighter than the conventional steel ropes. The ratio of
size of sheave to size of belt rope, in modern MRL is about
16:1 which is very less when compared to that of
conventional traction elevators. The smaller ratio allows the
smaller drive sheave and therefore this does not only save
the space but also it is energy efficient to operate (Harvey
and Sachs, 2005). Use of LED for lift car and the lift well as,
leads to about 5 to 10% energy savings. Incorporating
various methods simultaneously can yield an energy
saving of 30–35% within elevator classes (Sachs, 2005).
Rope developed with a carbon fiber core and a high -
friction coating, are extremely light and this reduces energy
consumption in high rise buildings (Asvestopoulos et al.,
2010). Further it mimimizes the weight of its moving
components, such as the hoisting ropes, compensating
ropes, counterweight, elevator car, and passenger load
(Chew et al., 2008; Akhavan et al., 2006; Al-Adaileh and Al-
Atawi, 2011; Al-Alawi et al., 2007).
Moreover, carbon fiber resonates at a completely different
frequency to steel and most other building materials. The
elevator downtime caused by building sway is reduced.
The weight bearing capacity of carbon polymer reinforced
fibre rope is better and the life of these ropes are also twice
as that of steel ropes (Barney, 1991; Bashiri and Badri, 2011;
Beckman, 1999).
2.3 Gearless and MRL
Modern gearless MRL lifts are provided with a load weighing
device to detect an overload condition within the car. The
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overload detecting strain gauge switch or pressure switch is
incorporated in the system. The gauge is fitted to the car
crown bar/rope anchor arrangement. This switch overrides
the car movement control and signal an alarm buzzer and
electronic message on the car indicator until such time as
the overload is reduced.
In view of the expectations of value for money from the
customers, the multinational elevator companies are
focusing to develop high speed and maximum travel span
MRLs. The gearless MRL machine unit and governor are
located in the overhead of the hoistway. The Gearless MRL
elevator is becoming the more popular choice amongst
mai n s t r e a m e l e v a t o r co m p a n i e s (C h e n g , 2 0 1 1 ;
Chennamaneni, 2006).
It is accepted that the maintenance of gearless MRL is
expensive, but it is rarely time consuming, provided the
support and services are prompt, when compared with
conventional elevators. Even though, inclusion of new
control, operation and safety features has increased the
complexities of MRLs, they are becoming more reliable
and safe. Troubleshooting complexity is also significantly
increased since it is often difficult for the service technician
to get all the components required to solve the problems.
Additional labour cost makes the MRLs to be most
expensive to maintain.
Economy, System Performance, safety and comfort are
the most important factor that needs to be complied for
stringent and regular inspection guidelines based on
elevator maintenance laws. Most of the defects can be
prevented by considering three major maintainability
criteria, i.e. design and specification, construction or
installation, and inspection and maintenance (Chew et al.,
2008).
The standard MRL represents a green technology since it
does not use oil and therefore no possibility of spill overs to
the environment. Further, most of the gearless MRL
components are manufactured off-shore, therefore
shipping is also greener.
The year 2004 may well be remembered in the elevator
industry as a watershed year. For low-rise applications,
these machine-room-less elevators are coming down in
cost. This technology is going to rapidly wipe out hydraulics
from the market.
Based on a brief review of elevator installations in past 3
years, it is observed from the data of Form-A (permission to
eret lift), Form-B (Lift erection completion report) and
licenses issued by Public Works Department (PWD) Electrical
Engineering Division that, gearless MRLs are being installed
extensively and traditional geared traction elevators have
become almost obsolete.
Until recently, low-rise elevators (up to five or six stories) were
typically hydraulic, and mid-rise elevators (up to 20 or 30
stories) were geared, traction machines. Hydraulic
elevators pump hydraulic fluid, moving a piston that
pushes the elevator cab up and lowers it back down
(Davenport and Prusak, 1997; Zander, and Kogut, 1995).
Selection and evaluation of lift suppliers is also as important
as selection of specification of elevators in modern
competitive environment to increase effectiveness and
utility due to an extensive variety of manufacturers. It has
become more and more complicated to meet the
challenges of international competitiveness, and as the
decision makers need to assess a wide range of alternative
suppliers based on a set of conflicting criteria. Because of
these reasons, supplier selection has got considerable
attention by the academicians and researchers (Jha et al.,
2013).
3. Multi Criteria Decision Approach for Selection
Minimizing cost of installation without sacrificing the safety,
reliability and ease of operation is one of the most desired
goals for a selection of elevator. Apart from cost, there are
many factors such as technical specifications, quality,
reliability of equipment, maintenance aspects, energy
efficiency, running costs, etc. that needs to be considered
for elevator selection. Considering the multiple criteria
decision requirement, the elevator selection can be
formulated as Multi Criteria Decision Making(MCDM)
problem. There are numerous MCDM techniques such as
Analytical Hierarchy Process (AHP), Technique to Order
Prefer enc e by Similar ity to Ideal S olution (TOPSIS),
Preference Ranking Organization Method for Enrichment
Evaluation (PROMETHEE), ELECTRE, VIKOR, etc. popularly
used in many equipment selection decisions (Temiz and
Calis, 2017).
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3.1 Analytical Hierarchy Process (AHP)
The analytical hierarchy process was developed by Saaty
(1980) which is based on additive weighing process. AHP
has been widely used in many MCDM problems and
researchers have applied many versions of AHP combined
with other approaches such as Fuzzy, Genetic algorithm,
etc. In application to the problem, AHP involves three major
stages: first, to form a hierarchical structure of criteria and
alternatives; second, make a pairwise comparison of the
decision criteria/alternatives and third, to prioritize the
alternatives based on relative ranking.
The stepwise procedure of AHP is presented as follows
(Görener, 2012):
Step 1: Construct the structural hierarchy.
Step 2: Construct the pairwise comparison matrix.
In this step, the pairwise comparison of the criteria is
performed. The 'n' criteria problem will result in a square
matrix (A) of size (n×n). In this matrix, the elements a (i, j= 1,
ij
2, 3 ….., n) corresponds to the weights of the criteria based
on the preference. This is given in equation (1).
(1)
Step 3: Construct normalized decision matrix
Step 4: Construct the weighted, normalized decision matrix
Step 5: Calculate the Eigenvector and the maximum Eigen
value.
Step 6: Calculate the consistency index & consistency
ratio.
The relation between the entries of the matrix A is defined as
the consistency and the Consistency Index (CI) can be
calculated using equation (2). Here, l represents the
max
maximum Eigen value.
(2)
Based on the consistency index, the Consistency Ratio (CR)
is calculated using equation (3). The CR decides whether
the evaluations are sufficiently consistent with the chosen
criteria weights and any further iterations or revisions are
needed. The consistency ratio has to be smaller than 0.1,
otherwise mo re iteration s of evaluation has to be
performed to improve the consistency.
(3)
The AHP methodology assists to determine the relative
rankings of the alternatives consistent with the criteria and
choose the best alternative based on the priority. AHP
Figure 2. Structural Hierarchy
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calculations can be done using electronic spreadsheets,
software packages, etc.
Conclusion
Modern elevators are a beautiful conglomeration of
mu ltid isc ipli nar y engi neer ing fi elds i nvol ving c ivil,
mechanical, electrical and electronics systems. A feature
based comparison of lift specifications shows that the latest
elevator technologies incorporate smooth gearless
microprocessor controlled magnetic drive motors directly
installed over the lift car itself. Space requirement is one of
the influential factors in new lift installations in high rise
buildi n g s. Tech n i c a l spec i f i c a t i o ns like G e n e r a l
Arrangement Drawing (GAD), Capacity, Speed (mps),
STOPS, Drive Power supply, Operation, Rescue, Machine
Traction Media, Car Finish, Car door and landing door
frame, Hand Rails, Ventilation, Flooring, Car fittings, Fire
Rating Doors, Hoist way Dimensions, Door Operator, Care
Operating Panel, Car Position Indicator, Power, Brakes,
Emergency Services, Emergency Car Light Unit, Door
screen, Door Time Protection, Emergency Alarm Bell, Extra
Door Time of Lobby and Parking, Door Open/Close Button,
Maintenance service/Guarantee Warranty, Civil work inside
shaft etc. are the most significant decision factors in the
installation of a modern elevator. A quick checklist
including reliability, maintenance and energy efficiency
would also be helpful. Rated load and size of the car should
be practicable.
Modern MRL incorporates gearless, Permanent Magnet
Sync hro nou s (PMS) moto rs re pla cing conve nti ona l
induction motors. The design of modern gearless MRL
elevators eliminates machine room requirement and
therefore saves substantial building space. Gearless MRL
technology can be used for both front and front and rear
open elevator cars. The gearless drive system uses 40% less
energy than the traditional geared lift. The PMS gearless
MRL drive technology powered by a 3VF inverter unit
directly connected to sheave controls the necessar y
torque throughout the full speed range of the elevator.
Regeneration Drive systems (regen) in most of the modern
elevators offers an excellent option in extensively travelling
busy elevators for conserving energy. However, a power
requirement for gearless MRLs in standby mode is little
higher compared to power requirements of hydraulic or
electrical elevator drives. Thus MRLs are energy efficient
during operation and requires significantly less service time.
For mid to low-rise applications (5 to 25 storeyed buildings),
gearless MRLs are becoming best options. Gearless MRLs
cater perfectly not only to the needs of the architects,
builders and users, but also to the environment by earning
carbon credits and national economics by saving energy.
Numerous options of elevators are available in the market
with different qualities and costs which make the selection
process a difficult task. For that reason, the MCDM
methods, which take into account multiple criteria and
rank the alternatives analytically, can be used effectively to
solve the selection problem.
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Dr. Vishal V. Shukla is working as Associate Professor at Shri Ramdeobaba College of Engineering and Management (RCOEM),
Nagpur, India. He holds a Ph.D in Mechanical Engineering (Biomechanics & Bio -Engineering) awarded by Visvesvaraya National
Institute of Technology (VNIT), Nagpur, India. He has managed 6 Lift installation projects (3 MRL & 3 Hydraulic) and also 350+ kW
Roof Top PV Solar Power plant project at RCOEM, Nagpur. He has to his credit a couple of patents, a book, about 15+ research
papers and a few consultancies. His areas of interest/expertise are Mechanical and Biological System Design, FEM, Solar Power,
Additive Manufacturing etc.
Dr. Pravin P. Tambe is working as an Associate Professor, at Department of Industrial Engineering, Shri Ramdeobaba College of
Engineering and Management (RCOEM), Nagpur,India. He holds a PhD in Industrial Engineering from Indian Institute of
Technology (IIT) Delhi, India. He has more than 15 years of academic experience. He is Fellow of Indian Institution of Industrial
Engineering. He has published research papers in International Journals published by Elsevier, Emerald, Springer, etc. and
International Conferences organized by POMS, IAENG, IEOM, etc. He is a reviewer to many International Journals like Computers
& Industrial Engineering, Reliability Engineering & System Safety, European Journal of Operational Research, Journal of
Manufacturing Technology Management and many International Conferences. His research interest mainly focuses on
Reliability, Maintenance Planning, Quality Control and Production Scheduling.
ABOUT THE AUTHORS
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