System Theories

JAHANGIRABAD INSTIUTE OF TECHNOLOGY
BARABANKI
Department of Mechanical Engineering
System Theories
RAVI VISHWAKARMA
10/06/17 Ravi Vishwakarma ,Assistant Professor JIT 1

System theory is the trans disciplinary study of the abstract
organization of phenomena, independent of their substance, type, or
spatial or temporal scale of existence. It investigates both the principles
common to all complex entities, and the (usually mathematical) models
which can be used to describe them. A system can be said to consist of
four things. The first is objects – the parts, elements, or variables within
the system. These may be physical or abstract or both, depending on
the nature of the system. Second, a system consists of attributes – the
qualities or properties of the system and its objects. Third, a system had
internal relationships among its objects. Fourth, systems exist in an
environment.
What is Systems Engineering?

Systems Engineering Principles
Start with Your Eye on the Finish Line
You should reach consensus at the very beginning of the project on
what will constitute success at the end. This means that the
stakeholders should start with an agreement of what the project should
accomplish and the metrics that will be used to measure the success of
the project. This initial focus on the finish line must be sustained by
project management as project development progresses and competing
interests and project complexities begin to dominate the day-to-day
work.

Concept of systems
The word system is derived from the Greek word “systema” which
means an organized relationship among functioning units or
components. A system exists because it is designed to achieve one or
more objectives. We come into daily contact with the telephone system,
the transportation system, the accounting system, the railway system,
the production system and for over four-decades, the computer system.
Similarly we talk of business and its organization as a system
consisting of the interrelated departments (sub systems) such as
production, sales, personnel and information systems, etc.

Application of a system
(i) Each system is composed of subsystems, which in turn are made
up of other subsystems, each subsystem being delineated by its
boundaries. The interconnections and interactions between the
subsystems are termed as interfaces. Interfaces occur at the
boundary and take the form of inputs and outputs.
(ii) A subsystem at the lowest level may not be defined to be
processor. The input and output are defined but not the
transformation process. This system is termed as a black box.
(iii) Each system has a boundary. The system is inside the boundary
and the environment is outside the boundary.

Implications of Systems Concept
The study of systems concept has three basic implications:
1.Interrelationships and interdependence must exist among the
components.
2.The objectives of the organization as a whole have a higher priority
than the objectives of its sub-systems. For example, computerizing
personnel applications must conform to the organization’s policy on
privacy, confidentiality and security, as well as making selected data
(e.g., payroll) available to the accounting division on request.
3.A system must be designed to achieve a predetermined objective.
(e.g. contact basis). The Barauni Refinery refines petrol and diesel
which is being supplied to (BKPL) Barauni- Kanpur Pipe Line.

A case study-Viscous lubrication system in wire drawing
These days a case study is used more and more in a preventive way rather
than as a therapy after a situation has broken down. Most frequent
application of the case study approach is in the study of persons or
situations, which have gone awry. A case study is based on assumptions.
a case study of viscous lubrication system in wire drawing is fully
concerned with application of system concepts in engineering—
identifications of engineering functions, system approach, engineering
activities matrix, defining the proposed effort, role of engineer,
engineering problem solving and concurrent engineering.

Steps In a Case Study
1.Determining present status:
The first step is to gather descriptive information which will determine,
as precisely as possible, the present status of the unit under
investigation. Here the investigator after knowing the problem tries to
find out the nature and extent of the problem.

2. Gathering background information:
Once the researcher is able to achieve an accurate description of the present situation,
he collects background data. Here the researcher collects information about and
examines the circumstances leading to the current status. At this stage, the investigator
compiles a reasonable list of the possible causes of the present situation. He formulates
the hypotheses about the true nature of the situation by making use of symptoms which
appear in the data by using the researcher’s past experiences with similar situations, and
by using the knowledge of the principles of human behavior.

3. Testing suggested hypothesis:
At this step the researcher gathers specific evidences in relation to each
of the hypotheses suggested from the background information just
gathered. The individual’s behavior is usually determined by several
factors. The researcher tries to locate the factors, which are influential
and therefore, are important. He tries to eliminate those, which are not.

4. Instituting remedial action:
The case studies are generally carried on to make an intensive
examination of problem cases. Therefore, the researcher tries to find out
how one or more of the hypothesized difficulties actually contributed to
the original difficulties. This is accomplished by instituting some remedial
or corrective program and then by examining as to what effect the change
has brought about.

Problem Formulation
Problem formulation is the name given to the following two steps:
1.Defining the Problem
2.Forming model.

System Theories
The trans disciplinary study of the abstract organization of phenomena,
independent of their substance, type, or spatial or temporal scale of
existence. It investigates both the principles common to all complex
entities, and the (usually mathematical) models which can be used to
describe them.

Black Box Approach
In order to achieve an overview of the operation of a system it is not
necessary to study the detailed functioning within each component.
When the detailed internal functioning within a component is ignored
and the component is regarded simply as a devise which transforms
input into output, it may be referred to as a black box.

Component Integration Approach
When we look closely at the environment of a system, we see that it too
consist of systems interacting with their environments. For example,
the environment of a person is full of other persons. If we now consider
a collection of such systems that interact with each other, that
collection could again be seen as a system. For example, a group of
interacting people may form a family, a firm, or a city.

State Theory Approach
The state of a system is represented by a set of one or more key
variables whose values completely define the condition of the system at
any instant of time. When a doctor investigates the stage of health of a
patient by measuring blood pressure, heart beat, condition of the eyes,
level of cholesterol ,level of sugar etc., The values of a primitive set of
state variables are being determined as a means of establishing the state
of a biological system.

Decision Process Approach
In the larger systems there arises the need to select effectively
alternative designs. Designers must make decision's, among others, as
to :
1.Energy Sources
2.Component Elements
3.Market
4.Design
5.Control
6.Material
7.Loads
8.Design Stress
9.Fabrication
10.Maintenance

System Modeling
The concept of models and modeling is a highly developed field od
science. Models are used in all fields e.g. Biology ,Physiology,
Engineering ,Chemistry, Biochemistry ,Physics and Economics etc.
A model is representation of a system in a convenient fashion so that
conjectures made about the performance of the system can be readily
tested. It is important to remember that the ‘model’ is meant to imply a
manifestation of a real thing.

Types of Models
Models can be classified as one of three categories:
1.Iconic
2.Analog
3.Mathematical

Mathematical Modeling
I view mathematical models as “mathematical constructions based on
real world settings and created in the hope that the model behavior will
resemble the real world behavior.” With this interpretation,
mathematical modeling is as much theoretical science as it is
mathematics. In contrast to applications, model analysis requires us to
determine the extent to which models are able to replicate real-world
phenomena before we accept mathematical answers as meaningful.

Mathematical modeling can be used for narrow questions that call for
numerical answers, but it can also be used for broad questions about
general behavior (e.g., for what ranges of parameter values will a
population go extinct?). Mathematical modeling requires
interdisciplinary skills that are seldom taught in any courses, and this is
one important reason why many students who have always had good
grades in mathematics ﬁnd themselves at a loss when they need to use
mathematics to do work in science. The purpose of this chapter is to
introduce modeling ideas and skills in a small number of simple
settings. These ideas and skills are then utilized in the remainder of the
text.

System Theories

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