Quantitative Techniques
Ans 2 Model :-A model is an abstraction of reality or a representation of a real object or situation. In other words, a model presents a simplified version of something. It may be as simple as a drawing of house plans, or as complicated as a miniature but functional representation of a complex piece of machinery. A model airplane may be assembled and glued together from a kit by a child, or it actually may contain an engine and a rotating propeller that allows it to fly like a real airplane.
A more useable concept of a model is that of an abstraction, from the real problem, of key variables and relationships. These are abstracted in order to simplify the problem itself. Modeling allows the user to better understand the problem and presents a means for manipulating the situation in order to analyze the results of various inputs ("what if" analysis) by subjecting it to a changing set of assumptions.
The 10 Main Types Of Modeling
1. Fashion (Editorial) Model
These models are the faces you see in high fashion magazines such as Vogue and Elle. Editorial models also usually work for top designers such as Marc Jacobs, Prada, and Gucci. As a whole, editorial modeling tends to be the most selective. Most Editorial models are incredibly tall, slim, and usually are the ‘complete package.’
2. Runway Model
These models are found on the catwalk and are hired to showcase a designer’s clothing line. Due to the precise sizes of the designer’s clothing, runway models are often a certain height and size. If you are at least over 5’9 then this type of modeling could be for you.
3. Swimsuit & Lingerie Model
These models specialize in showing off either swimsuits or lingerie. This model type is usually someone a bit more voluptuous and curvier. These models also tend to model sleepwear, summer wear, and other forms of undergarments.
4. Commercial Model
Commercial Models are not restricted by age, height, or size. Therefore, this modeling type is the most open to diverse and new talent. Commercial models advertise a wide range of products in catalogs, campaigns, and commercials.
5. Fitness Model
These models tend to be fit, toned, and athletically built. This of course makes sense as these models are tasked with wearing fitness attire. Fitness models are also found in commercials that involve demonstrating fitness routines.
6. Parts Model
Parts Models specialize in modeling their hands, arms, feet, and legs. A hand model can book a job involving jewelry, whereas a foot model can book a job with a shoe company. Both can book a job involving nail and beauty care. As a whole, clients look for a parts model that has well-proportioned body parts that fit standard shoes and jewelry.
7. Fit Model
A fit model is a model that works behind the scenes and helps fashion houses get the sizing and fit right before the garment is sent off to be manufactured. Fit models are a diverse group in terms of body shape since there’s a need for fit models to represent every size a garment comes in.
8. Promotional Model
This type of model books jobs that help sell or promote a certain commodity. Promotional models are often found at trade shows and other live events. As a whole, these models must be personable, outgoing, and have a strong knowledge of the product they are representing.
9. Glamour Model
Glamour modeling is centered on appearance, including facial beauty and body shape. These models are usually curvier than editorial models and often book swimsuit and lingerie photoshoots. Glamour models tend to pose more suggestively than typical editorial or commercial models.
10. Print Model
Print models are often found in magazines, billboards, campaigns, booklets, flyers, and posters. These models usually have clear skin and a nice smile. While some of these models are selling a product, others are simply photographed based on the needs of the client.
Advantages of modelling and simulation
Can be safer and cheaper than the real world.
Able to test a product or system works before building it.
Can use it to find unexpected problems.
Able to explore ‘what if…’ questions.
Can speed things up or slow them down to see changes over long or short periods of time.
Disadvantages of modelling and simulation
Mistakes may be made in the programming or rules of the simulation or model.
The cost of a simulation model can be high.
The cost of running several different simulations may be high.
Time may be needed to make sense of the results.
People’s reactions to the model or simulation might not be realistic or reliable.
Ans 3 Sequencing Problems Introduction
When a number of jobs are given to be done and they require processing on two or more machines, the main concern of a manager is to find the order or sequence to perform these jobs. We shall consider the sequencing problems in respect of the jobs to be performed in a factory and study the method of their solution. Such sequencing problems can be broadly divided in two groups. In the first one, there are n jobs to be done, each of which requires processing on some or all of the k different machines. We can determine the effectiveness of each of the sequences that the technologically feasible (that is to say, those satisfying the restrictions on the order in which each job must be processed through the machines) and choose a sequence which optimizes the effectiveness. To illustrate, the timings of processing of each of the n jobs on each of the k machines, in a certain given order, may be given and the time for performing the jobs may be the measure of effectiveness. We shall select the sequences for which the total time taken in processing all the jobs on the machines would be the minimum.
In this unit we will look into solution of a sequencing problem. In this lesson the solutions of following cases will be discussed:
a) n jobs and two machines A and B, all jobs processed in the order AB.
b) n jobs and three machines A, B and C all jobs processed in the order ABC
c) Problems with n jobs and m machines.
Ans 2 What is Single channel?
This is the use of one channel to market a company’s products and services. As such the brand’s communication is centered on the chosen channel. This could be an online channel, traditional retail, face to face selling or catalogue.
Advantages of using single-channel marketing strategy include;
It is cost-efficient as brands only utilize one marketing channel
It helps build a loyal customer base
It is simple to operate in terms of tracking inventory, customer service and shipping inventory.
It, however, has disadvantages including;
It may not be as speedy in response as needed
It is difficult to keep up with technological development while using one channel, hence the marketing efforts do not reach the optimum customer base
The brand loses its prospective customers who use alternative marketing channels
What is Multi-channel?
This is the use of more than one channel for brands marketing and communication. This method accommodates where, how and when consumers make purchases, and focuses on ensuring the products or services are available when needed. It hence makes it easy for consumers to shop. The multi-channel marketing strategy also enhances a firms’ ability to reach current customers and also reach a wider number of prospective consumers.
The advantages of the multi-channel marketing strategy include;
The presence of the brand to its consumers on different channels boosts chances of sales
Due to the exposure to new markets, it is easy to reach new customers
A brand can focus on target selling, considering some products sell better on different targeted marketplaces
The brand reduces the chances of fake products in the market as its products are readily available.
Differences between Single-channel and multi-channel marketing
Cost-efficiency
While single-channel is cost-efficient as it uses one marketing channel, multi-channel is expensive to operate and maintain.
Customer base
Single-channel has a narrow customer reach while multi-channel has a wide customer reach.
Organizational complexity
While single-channel is simple to operate in terms of tracking inventory, customer service and shipping inventory, multi-channel requires good organizational infrastructure and discipline.
Ans 3 Types of queue
Structured queues
Here people form a queue in a fixed, predictable position, such as at supermarket checkouts, and other retail locations such as banks or airport security. In the field of facilities management, structured queues are commonly known with different names like "Queue Managers" or "Crowd Controllers" or "Public Guidance Systems". Very often, queue management systems are set up to manage ticket ranking for a service (with or without a numbered ticket) with identification and thus enable a serene and stress-free waiting. Extending the different possibilities, planned reception by appointment and remotely rank allocation on or through Short Message Service can also be included.[2] A more rudimentary (or in some cases, supplementary) manual element to structured queue management involves the addition of a member of human staff to deliver a system, monitoring structured queue lengths in order to guide people in a queue or to make adjustments to speed up service (e.g. fetching more cashiers). Such systems are used in UK supermarkets, for example, where the addition of a 'host' role or Customer Service Manager may occur.
Unstructured queues
Where people form a queue in unpredictable and varying locations and directions.[3] This is often the case in some forms of retail, taxi queues, ATMs and at periods of high demand in many situations. In the busiest places, physical barriers and guides are used to funnel people into a line as they arrive.
Mobile queue, virtual queue, and online queue
One stop app with various businessess and institutions could be a better option in customer point of view.
Allowing customers to use their mobile phone to view real-time queue data and select a reason that they want to visit your service center. Customers are free to carry on their day and don't have to wait in a waiting area for too long. Customers can wait anywhere else while waiting for their turns. They can receive notifications via SMS, App or Emails informing them about theire turn and when ready to be seen, they are called forward for service.
Mobile phone text messages for a queue at a motor vehicle office.
Mobile queues especially the online ones can also include real-time queue data statistics as well as real-time customer feedback. Qiwii.id[4] is one example of queuing system that can provide real time data about queue and the estimation of waiting time.
Mobile queues require the customer to install apps to their phone before getting into the queue. The time to install may extend the persons actual wait time for the first visit. There are many option of queuing app and not every business uses the same app, customers can end up with hundreds of apps on their device. The one stop app for many businesses and institutions could be a better option in customer point of view. Mobile queue app for single business/institution will only be beneficial for customers that visit the same place on a regular basis.
Ans 4 What Is Project Crashing?
Project crashing is when you shorten the duration of a project by reducing the time of one or more tasks. Crashing is done by increasing the resources to the project, which helps make tasks take less time than what they were planned for. Of course, this also adds to the cost of the overall project. Therefore, the primary objective of project crashing is to shorten the project while also keeping costs at a minimum.
Just as the triple constraint says, if you reduce the duration of the project, or its time, then costs will in turn have to increase. It’s a trade off. Crashing project management accounts for the triple constraint, in that to achieve it, you include additional resources or reduce the project requirements or scope. However, such drastic measures cannot be implemented without the sponsor or primary stakeholders agreeing to the changes.
A result of project crashing can be a change to the critical path and the emergence of a new, different critical path. Project crash management requires that you return to your project schedule to make sure you’re aware of changes that have occurred there because of the project crashing.
All of this is made easier by project management software with scheduling tools. With ProjectManager, you can build a project schedule in a matter of minutes on our Gantt charts, and then filter for the critical path. From there, you can make all the necessary changes you need to adjust your schedule and deliver on time and under budget. Get started for free.
What Prompts Crashing in Project Management?
When would a project manager want to increase investment to complete the project earlier? After all, a lot of time and effort went into the project planning and schedule. Obviously, since project crashing requires higher costs, it wouldn’t be used unless there’s an emergency.
One reason for using project crashing would be if the project was scheduled unrealistically, and this wasn’t clear until the project has already been executed. This can even happen at the planning stage if the sponsor, customer or stakeholder insist on a due date that isn’t feasible.
Another reason is that, during the process of a change control analysis (which shows impact on the time, cost, scope or other project factors), an issue comes up that must be addressed immediately. As issues arise in the course of managing a project that take it off track, the project manager must figure out a way to lock back to the schedule baseline.
As noted above, other than project crashing, there is the fast tracking method. Though we’re discussing project crashing, it’s important to touch on when fast tracking is preferable. Sometimes you can use either, but if the project is already over-budget and you don’t have funds, then fast tracking is the likely option.
The replacement problems are concerned with the situations that arise when some items
such as men, machines and usable things etc need replacement due to their decreased
efficiency, failure or breakdown. Such decreased efficiency or complete breakdown may either
be gradual or all of a sudden.
If a firm wants to survive the competition it has to decide on whether to replace the out dated
equipment or to retain it, by taking the cost of maintenance and operation into account. There are
two basic reasons for considering the replacement of an equipment.
They are (i) Physical impairment or malfunctioning of various parts.
(ii) Obsolescence of the equipment.
The physical impairment refers only to changes in the physical condition of the equipment
itself. This will lead to decline in the value of service rendered by the equipment, increased
operating cost of the equipments, increased maintenance cost of the equipment or the
combination of these costs. Obsolescence is caused due to improvement in the existing Tools
and machinery mainly when the technology becomes advanced therefore, it becomes
uneconomical to continue production with the same equipment under any of the above
situations. Hence the equipments are to be periodically replaced.
Sometimes, the capacity of existing facilities may be in adequate to meet the current demand.
Under such cases, the following two alternatives will be considered.
1. Replacement of the existing equipment with a new one
2. Argument the existing one with an additional equipments.
Ans 5 Introduction
The replacement problems are concerned with the situations that arise when some items such as machines, men, electric appliance etc. need replacement due to their decreased efficiency, failure or breakdown. The deteriorating efficiency or complete breakdown may be either gradual or all of a sudden. A replacement is called for whenever new equipment offers more efficient or economical service than the existing one. The problem in such situation is to determine the best policy to be adopted with respect to replacement of the equipment. In case of items whose efficiency go on decreasing according to their age, we have to spend more and more money on account of increased operating cost, increased repair cost, increased scrap, etc. In such cases the replacement of an old item with a new one is the only alternative to prevent such increased expenses. Thus, it becomes necessary to determine the age at which replacement is more economical rather than continuing with the same.
Types of Replacement Situations
The replacement situations may be classified into four categories:
a) Replacement of items that become worse with time e.g. milk plant machinery, tools, vehicles, equipment etc.
b) Replacement of items which do not deteriorate with time but break down completely after certain usage e.g. electric tubes, machinery parts etc.
c) Replacement of items that becomes obsolete due to new developments.
d) The existing working staff in an organization gradually reduces due to death, retirement and other reasons.
The problem is to decide the best policy to adopt with regard to replacement. The need for replacement arises in a number of different situations so that different types of decisions may have to be taken. For example:
a) It may be necessary to decide whether to wait for certain items to fail, which might cause some loss, or to replace the same in advance, even at a higher cost.
b) An item can be considered individually to decide whether or not to replace immediately.
c) It is necessary to decide whether to replace by the same item or by an improved type of item.
Ans 1 Random numbers explained
For a number in a sequence or distribution to be truly random, it must be independent. The independence of numbers means there is no correlation between successive numbers. In addition, these numbers should occur in the distribution with approximately the same frequency.
Random numbers are almost always derived from a set of single-digit decimal numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. The task of generating random digits from that set of numbers by physical means is not trivial. A common scheme is the selection of numbered pingpong balls from a set of 10, as frequently seen in lotto games and lotteries.
Each ball bears a digit and is circulated in a container by an air jet. After each number is selected, the ball with that number is returned to the set. The balls are again blown around before another ball is selected. The process continues until the desired set of random numbers has been generated.
Ans 2 Concept
Sequencing problems are concerned with determining the best order (sequence) for a series of jobs to be performed on a finite number of service facilities (such as machines) in some well-defined technological order in order to maximise some efficiency metric such as total elapsed time or overall cost.
Given
No passing rule in sequencing problem
Find
We are asked to explain what do you mean by no passing rule in sequencing problem.
Solution
The absence of a passing rule indicates that passing is not permitted, i.e., the same order of jobs is maintained across all machines. If n jobs are to be handled in the order AB through two machines A and B, then each task will travel to machine A first and then to B.
Ans 3 What Is Project Crashing?
Project crashing is when you shorten the duration of a project by reducing the time of one or more tasks. Crashing is done by increasing the resources to the project, which helps make tasks take less time than what they were planned for. Of course, this also adds to the cost of the overall project. Therefore, the primary objective of project crashing is to shorten the project while also keeping costs at a minimum.
Just as the triple constraint says, if you reduce the duration of the project, or its time, then costs will in turn have to increase. It’s a trade off. Crashing project management accounts for the triple constraint, in that to achieve it, you include additional resources or reduce the project requirements or scope. However, such drastic measures cannot be implemented without the sponsor or primary stakeholders agreeing to the changes.
Ans 4 Replacement Policies
Basic to the implementation of virtual memory is the concept of demand paging. This means that the operating system, and not the programmer, controls the swapping of pages in and out of main memory as they are required by the active processes. When a non-resident page is needed by a process, the operating system must decide which resident page is to be replaced by the requested page. The part of the virtual memory which makes this decision is called the replacement policy.
There are many approaches to the problem of deciding which page to replace but the object is the same for all--the policy which selects the page that will not be referenced again for the longest time.
Examples:
First In First Out (FIFO):
The page to be replaced is the "oldest" page in the memory, the one which was loaded before all the others
Least Recently Used (LRU):
The page to be replaced is the one which has not been referenced since all the others have been referenced
Last In First Out (LIFO):
The page to be replaced is the one most recently loaded into the memory
Least Frequently Used (LFU):
The page to be replaced is the one used least often of the pages currently in the memory
Optimal (OPT or MIN):
The page to be replaced is the one that will not be used for the longest period of time. This algorithm requires future knowledge of the reference string which is not usually available. Thus, this policy is used for comparison studies
The anomalies associated with replacement policies like FIFO have led to the interest in the policies like LRU which do not suffer from such anomalies. They are known as stack algorithms.
Ans 5 Group replacement policy: under this policy, it is decided to replace all the items after a certain time period irrespective of the facts that items have failed or have not failed with an option that if any item before the optimal time, it may be individually replaced.
A preventive maintenance system which replaces groups of items such as lightbulbs at predetermined intervals, even though they may not all have come to the end of their life.
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