...Modelos cuantitativos y de optimización 20 de febrero de 2015 Filas en los supermercados, características de los clientes y políticas para el manejo de las líneas de espera en los supermercados El termino caja rápida, caja preferencial (para discapacitados, embarazadas y personas de la tercera edad) o solo efectivo son términos comunes en los supermercados del Reino Unido y en la mayoría de los supermercados en el mundo para evitar grandes filas de espera para poder cobrarle al cliente ¿Tienen las cadenas de supermercados que tener políticas generales acerca de las líneas de espera para todas sus tiendas o tiene que adaptarlas a la zona en donde está ubicado el supermercado? Este artículo, escrito por Roger Bennett, tiene como propósito encontrar la respuesta a esta pregunta con pruebas estadísticas. Las líneas de espera es un factor significativo al momento de calificar el servicio de un supermercado. En este tipo de servicios se está utilizando un modelo tipo M/M/S dado que tiene varios servidores con filas propias. El disgusto de los clientes acerca de las filas de espera se basa en la idea de que las personas suelen experimentar malestar emocional mientras espera en línea, siente que son momentos de su vida desperdiciados dado que o tienen otras actividades con mayor grado de importancia o tienen un perfil psicológico estresante y de impaciencia. Para la investigación, el consumidor se dividió en dos tipos; “Tipo A” son individuos que poseen un exagerado sentido...
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...The waiting line or queue management is a critical part of service industry. It deals with issue of treatment of customers in sense reduce wait time and improvement of service. Queue management deals with cases where the customer arrival is random; therefore, service rendered to them is also random. A service organization can reduce cost and thus improve profitability by efficient queue management. A cost is associated with customer waiting in line and there is cost associated with adding new counters to reduce service time. Queue management looks to address this trade off and offer solutions to management. Queuing System To solve problems related to queue management it is important to understand characteristics of the queue. Some common queue situations are waiting in line for service in super-market or banks, waiting for results from computer and waiting in line for bus or commuter rail. General premise of queue theory is that there are limited resources for a given population of customers and addition of a new service line will increase the cost aspect to the business. A typical queue system has the following: Arrival Process: As the name suggests an arrival process look at different components of customer arrival. Customer arrival could in single, batch or bulk, arrival as distribution of time, arrival in finite population or infinite population. Service Mechanism: this looks at available resources for customer service, queue structure to avail the service and...
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...Front is the slot in the array spot for 0. The index 0 is where front is placed. The Rear variable is waiting for a value to be inserted to take a spot. This variable will always be the value that was last inserted to the array. Q4: What is the difference between Rem and Peek operations? The operations remove deletes the value at the top of the array. In other words on the rear variable. The peek operation returns the value that the variable rear is pointing to. Q5: What technique in array it used to allow 50 inserted into the queue? Once the array was filled all the way to the top, the pointer came back to the bottom of the array where we had deleted two values. It came down to index 0 and stored the value 50. Q6: What is the difference between priority queue and the regular queue at insertion operations? There is a difference between priority and regular queue. Regular queue stores the value at the next slot open at the top of the array. Priority queue stores the value from largest to smallest. Therefore, it has to make space if the value has to go in the middle of the array. [pic] [pic] [pic] [pic] [pic] [pic] [pic] [pic]...
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...located at Maskan (Opposite Maskan gate, Karachi University) on the basis of which a young student who lives in IBA Hostel would make a choice of where to go. The first part of the model has listed the information about the stores selling groceries based on certain store characteristics like cleanliness, organization of shelves, spacious, friendly employees, total travel time, queues at the cash counters, availability of daily usage products, in store temperature and prices in relative terms. The total travel time, shop open time and queue at cash counter affect my beliefs about the convenience of the stores. The friendly employees, spacious and organized shelves store affects my belief about availability of product information. The prices are directly linked with the store being economical. Assortment is effected by the availability of a variety of daily usage products. A. Information About Stores Selling Groceries Store Characteristics Taimooria Home Needs Shop open time (relatively) Long Short Organized shelves No Yes Spacious No Yes Friendly Employees Yes No Total Travel Time (Minutes) 10 15 Queue at Cash Counter Long Short Availability of Daily Usage Products Excellent Good Prices (relatively) Low High The below table shows the beliefs about stores performance benefits on the basis of convenience, economy, assortment and availability of product information. Ratings are made on the basis of the scale ranging from 10 being excellent and 1 being poor. This shows...
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...Adaptive Traffic Control System Performance measure against which our proposed policy to be tested is green time utilization. This performance measure is estimated by measuring the green time during which vehicles are served for an instance of a given phase and then dividing by the total length of the green time instance (i.e. minimum and maximum green time) The supporting data for green time utilization are as follows: * Allocated minimum and maximum green time * vehicle departure times * Saturation headway These data can be retrieved from the Signal control data and stop line detector. Our objective is to maintain ideal state as long as possible if control system deviates from this ideal state to (over-utilization) or (under-utilization) then by using adaptive control strategy system will take actions by changing existing policy. Objective: max.8≤Ugfk<1 Subject to constraints: g minfk≤gfk≤g maxfk (1) f=AFgfk≤C (2) Here, Ugf= Average time taken by vehiclesAvailable time Ugf=number of departures in phase f× hsat{gmin, gmax} Ugminf= number of departures in phase f× hsat{gmin}, Ugmaxf= number of departures in phase f× hsat{gmax} So, theoretically the green time utilization should follow following condition to be remain in ideal...
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...June 9, 2013 Section 2, Team 9 Managing Capacity and Lead Time at Littlefield Technologies – Team 9’s Summary The purpose of this simulation was to effectively manage a job shop that assembles digital satellite system receivers. The objective was to maximize cash at the end of the product life-cycle (270 days) by optimizing the process design. REVENUE 25000 20000 15000 10000 5000 1 9 17 25 33 41 49 57 65 73 81 89 97 105 113 121 129 137 145 153 161 169 177 185 193 201 209 217 225 233 241 249 257 265 Total Revenue Demand DAYS 0 Figure 1 : Revenue and demand DEMAND 25 20 15 10 5 0 As shown by the figure above, total revenues generally followed the same trend as demand. The few sections of negative correlation formed the basis for our critical learning points. Although the process took a while to completely understand during the initial months of the simulation, the team managed to adjust, learn quickly and finish in 7th place with a cash balance of $1,501,794. For the purpose of this report, we have divided the simulation into seven stages after day 50, explicating the major areas of strategically significant decisions that were made and their resulting effects...
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...Devry GSCM 520 Week 4 Quiz IF You Want To Purchase A+ Work Then Click The Link Below , Instant Download http://www.hwspeed.com/Devry-GSCM-520-Week-4-Quiz-5906676.htm?categoryId=-1 If You Face Any Problem E- Mail Us At JOHNMATE1122@Gmail.Com Page 1 Question 1. 1. (TCO 7) Using the assembly-line balancing procedure, which of the following is the theoretical minimum number of workstations if the task times for the six tasks that make up the job are 4, 6, 7, 2, 6, and 5 minutes and the cycle time is 10 minutes? (Points : 3) Three Five Six Eight None of the above Question 2. 2. (TCO 7) You have just determined the actual number of workstations that will be used on an assembly line to be eight using the assembly-line balancing procedure. The cycle time of the line is 10 minutes and the sum of all that tasks required on the line is 60 minutes. Which of the following is the correct value for the resulting line's efficiency? (Points : 3) 0.500 0.650 0.750 0.850 None of the above Question 3. 3. (TCO 7) Which of the following is not a step in developing a manufacturing cell layout? (Points : 3) Grouping parts into families that follow a common sequence of steps Identifying dominant flow patterns of parts families as a basis for location of processes Physically grouping machines and processes into cells Disposing of left-over machinery and outsourcing ungrouped...
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...Did you ever wonder why it seems to take ages getting to the front of a queue? As referred to a survey done by an auction site, throughout our lifetime we spend six months waiting in a queue, which is nearly equivalent to three days over a year. What makes the survey more interesting is, it revealed just hanging around on platforms waiting for the train, or queuing at bus stops, actually takes up 653 hours over a lifetime. These scenarios proved that a queue is indeed a common every-day experience. Nevertheless, what is a queue and what makes a queue a fair and ethical queue? A queue is generally being defined as a line people or things waiting to be attended or to proceed, usually in sequential order beginning from the front or top of the...
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...Question 1 Change the following infix expression postfix expression. (A + B)*C+D/E-F Question 2 Suppose a 3d array LA is declared using LA(3:8, -4:1, 6: 9), base(LA)=200, w=4. find loc of LA[2,-2,5]. (Row major order). Question 3 Convert the expression (True && False) || !(False || True) to postfix expression. Show the contents of the stack at every step. Question 4 Use a stack to evaluate the following postfix expression and show the content of the stack after execution of each operation. Don't write any code. Assume as if you are using push and pop member functions of the stack. AB-CD+E*+ (where A=5, B=3, C=5, D =4, and E=2) Question 5 Evaluate the following postfix expression using a stack and show the contents of stack after execution of each operation : 50,40,+,18, 14,-, *,+ Question 6 Evaluate the following postfix expression using a stack and show the contents of stack after execution of each operation : TRUE, FALSE, TRUE, FALSE, NOT, OR, TRUE, OR, OR, AND Question 7 Write a program for creating polynomial using linked list? Question 8 Each node of a STACK contains the following information, in addition to required pointer field : i) Roll number of the student ii) Age of the student Give the structure of node for the linked stack in question TOP is a pointer which points to the topmost node of the STACK. Write the...
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...process. The similarity of how people wait in queues in a service operation and in a manufacturing operation is as follows; An example of a service operation that requires queuing is the transport service, Airlines for instance; what is similar between a manufacturing operation and this service operation is the storage area (departure), passengers are required to queue for ticket and immigration check and then they wait in the departure hall in order for other required stages of the process to be carried out, which might also lead to favorable decision or likewise. Buffering inventory in this case are, • Ticket check prior to • Boarding prior to • Maintenance check prior to • Weather report prior to The block/starve that may occur in this kind of service is the issue of bird-cast, unfavorable weather and so on, and this will lead to changing the time the service is suppose to be rendered. The slightest differences between manufacturing buffering inventories and service buffering inventories are; 1. Service buffering inventories involves humans, unlike manufacturing operation that involves static entities. 2. In Service operation entities are dependent on the provider. In service operations customer reaction to a situation may be at a disadvantage to the firm’s revenue intake. For example they are two eateries in the same vicinity but the one prefer by the customer is eatery A, so he/she goes to eatery A but because the queue and the time frame of rendering the service in...
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...Error Message: Deficit of SL Unrestricted-use 2 EA: 21GP84 004 0001 Issue: Queue failed because the stock levels on ECC and EWM are not in sync. In this case the available stock is less by 2 EA of product 21GP84. Reason: There are multiple reasons to have the above error triggered. But the main cause of this error is having the stock levels out of sync in both EWM and ECC systems. Root Cause: There are multiple reasons to have the systems (EWM and ECC) out of sync and queues to fail with Deficit of stock issue, some of them are listed below, 1. When someone manually posts inventory by using the inventory sync program /SCWM/ERP_STOCKCHECK, without checking if there are any open Queues or other process updates. 2. When someone used mass posting transaction /SCWM/POST to change the stock status from available to block or blocked to available, queues are failing if any of the product is out of sync in the system, then it will stop the posting change for all the products in the mass list. 3. If the queue for goods movement EWMMEWMGOODSMVT* is not monitored properly, for all the material movements in EWM system will trigger only on queue name with multiple LUWs and if any of the LUW movement is stuck for any reason, then other LUW’s will get piled up and waiting for the first one to clear. Resolution: 1. Manual Inventory Sync by using transaction /SCWM/ERP_STOCKCHECK: Business is not supposed to use this transaction to sync the stock levels on ECC and EWM. We...
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...manage them is one of the most important areas in operation management. In companies or in private life, there are instances of procedures which generates waiting lines or queues. The reason why these waiting lines occur is for the present services facility is inadequate to provide service at that instance. As an examples when people travel by airplanes, I have personal involvements with numerous types of waiting lines or queues. To buy tickets for a movie, I normally have to stand in line at movie theater ticket office. When I arrive at an airport most of the time I stand in line to check baggage, then I stand in line again to get a seat assignment. After that I line up again for the TSA security checkpoint and the again for the last time when waiting to board the plane to scan the boarding passes. I also wait when I am inside the plane, I wait for those ahead of me to take their seats. And finally, we may wait for baggage to arrive and then for ground transportation. I think this quote is very important and says a lot about waiting lines. “Perhaps the biggest influence on our feelings about lines, though, has to do with our perception of fairness. When it comes to lines, the universally acknowledged standard is first come first served: any deviation is, to most, a mark of iniquity and can lead to violent queue rage. Last month a man was stabbed at a Maryland post office by a fellow customer who mistakenly thought he’d cut in line. Professor Larson calls these unwelcome intrusions...
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...visiting a store, analogous to requests arriving at a device. Long Term Averages • Queuing theory provides long term average values. • It does not predict when the next event will occur. • Input data should be measured over an extended period of time. • We assume arrival times and service times are random. • • • • Assumptions Independent arrivals Exponential distributions Customers do not leave or change queues. Large queues do not discourage customers. Many assumptions are not always true, but queuing theory gives good results anyway Queuing Model Q W λ Tw Tq S Interesting Values • Arrival rate (λ) — the average rate at which customers arrive. • Service time (s) — the average time required to service one customer. • Number waiting (W) — the average number of customers waiting. • Number in the system (Q) — the average total number of customers in the system. More Interesting Values • Time in the system (Tq) the average time each customer is in the system, both waiting and being serviced. Time waiting (Tw) the average time each customer waits in the queue. Tq = Tw + s Arrival Rate • The arrival rate, λ, is the average rate new customers arrive measured in arrivals per time period. Common units are access/second • The inter-arrival time, a, is the average time between customer arrivals. It is measured in time per customer. A common unit would be seconds/access. • a=1/λ Random Values • We assume that most of the events we are interested in occur randomly...
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...and two top pointers. Explain why this may not be a space wise efficient implementation. A stack is a last in first out (LIFO) data type. A stack can be implemented using arrays where the data is stored in continuous memory locations. We have two operations in a stack push and pop. Since it has continuous memory allocated, if we try inserting data it gets saved in that free space present in either of the stacks. This is not a space wise efficient implementation because data is stored statically. In this case one stack can be full while the other is empty. 2. Using the basic queue and stack operations, write an algorithm to reverse the elements in a queue. Create an empty stack While the queue is not empty Remove a value from the queue and push it onto the stack While the stack is not empty Pop a value from the stack and add it to the queue. 3. Assume that 'Stack' is the class described in this section with 'StackType' set to into and STACK_CAPACITY or myCapacity set to 5. Give the value of 'myTop' and the contents of the array referred to by 'myArray' in the Stack s afer the code segment is executed, or indicate why an error occurs. Stack s; s.push(1); s.push(2); s.push(3); s.pop(); s.push(4); s.push(5); s.pop(); s.pop(); In a stack it is last in first out so When we push items on to it we have 1 first then 2 and then 3 We have pop so, we pop 3 since it is the last element Then again we have 4 then 5 Now we have two pops...
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...Hybrid Delivery System Layout Reason of existence: * For businesses in order to better respond to different market demands. * Companies align their delivery system to the characteristics of the market by rearranging the layout of their facilities. Examples of differentiated layout designs * Cellular Layout : a mix of functional and product layout * Nagare cellular layout ( sub-category of the previous) : Used for customized products and of low volume production * Transfer line layout : For high volume products and of standard nature Other Layout Formats * Flexing process layouts to reflect varying levels of demand Examples: car assembly plants, bank and post office layouts, fast food restaurants process layouts) * Flexible office layouts Impact of IT on Delivery systems and layouts * Automated Banking * Call centres Detailed Layout Design Decision making about: * The position of staff, processes, equipment * The position, size and number of other facilities not belonging to the delivery system * The number of other requirements (entrances, exits, …, elevators) * The space that will be allocated to the above areas Must also be defined: * The steps involved in delivering products or services * The followed sequence * The process routes (Space restrictions must be considered) The features of good layouts * System flow charting * Use of space * Use of equipment * Cost...
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