Revisa el libro de Pruyt (2013) y responde a las preguntas de opción múltiple listadas a continuación. Al entregar tu actividad sólo indica la opción seleccionada.
Capítulo 3:
Multiple Choice Question 2, página 69 (1 punto) Respuesta: (d)
Multiple Choice Question 3, página 70 (1 punto) Respuesta: (c)
Multiple Choice Question 4, página 70 (1 punto), Respuesta: (d)
Multiple Choice Question 5, página 71 (1 punto), Respuesta:(c)
Multiple Choice Question 6, página 71 (1 punto), Respuesta:(d)
Multiple Choice Question 8, página 72 (1 punto), Respuesta:(a)
Multiple Choice Question 9, página 72 (1 punto), Respuesta: (b)
Multiple Choice Question 12, página 74 (1 punto), Respuesta:(a)
Multiple Choice Question 13, página 74 (1 punto), Respuesta: (c)
Multiple Choice Question 14, página 75 (1 punto), Respuesta:(d)
Multiple Choice Question 17, página 76 (1 punto), Respuesta: (a)
Multiple Choice Question 19, página 78 (1 punto) Respuesta: (c)
Capítulo 7:
Multiple Choice Question 1, página 104 (1 punto), Respuesta: (d)
Multiple Choice Question 2, página 104 (1 punto), Respuesta: (c)
Multiple Choice Question 3, página 104 (1 punto), Respuesta:(d)
Multiple Choice Question 6, página 106 (1 punto), Respuesta: (d)
Multiple Choice Question 8, página 107 (1 punto), Respuesta: (a)
Multiple Choice Question 11, página 108 (1 punto), Respuesta: (c)
Multiple Choice Question 12, página 109 (1 punto), Respuesta: (b)
Multiple Choice Question 16, página 112 (1 punto) Respuesta: (a)
Introducción:
On 3 August 2009, media reported about an outbreak of pneumonic plague in north-west China:
“A second man has died of pneumonic plague in a remote part of north-west China where a town of more than 10,000 people has been sealed off. […] Local officials in north-western China have told the BBC that the situation is under control, and that schools and offices are open as usual. But to prevent the plague [from] spreading, the authorities have sealed off Ziketan, which has some 10,000 residents. About 10 other people inside the town have so far contracted the disease, according to state media. No-one is being allowed [to] leave the area, and the authorities are trying to track down people who had contact with the men who died. […] According to the WHO, pneumonic plague is the most virulent and least common form of plague. It is caused by the same bacteria that occur in bubonic plague – the Black Death that killed an estimated 25 million people in Europe during the Middle Ages. But while bubonic plague is usually transmitted by flea bites and can be treated with antibiotics, [pneumonic plague, which attacks the lungs, can spread from person to person or from animals to people], is easier to contract and if untreated, has a very high case-fatality ratio.” (BBC 03/08/2009)
Descripción del caso:
You are asked to make a SD model of this outbreak. Use the following assumptions: The total population of Ziketan amounted initially to 10000 citizens. New infections make that citizens belonging to the susceptible population become part of the infected population, which initially consists of just 1 person. The number of infections equals the product of the infection ratio, the contact rate, the susceptible population, and the infected fraction. Initially, the normal contact rate amounts to 50 contacts per week and the infection ratio to a staggering 75% per contact. The infected fraction equals of course the infected population over the sum of all other subpopulations. If citizens from the infected population die, they enter the statistics of the deceased population, else they are quarantined to recover. The recovering could be modeled simplistically as (1 − fatality ratio) ∗ infected population / recovery time. Suppose for the sake of simplicity that the average recovery time and the average decease time are both 2 days. The fatality ratio depends on the antibiotics coverage of the population which –in this poor part of China– is 0% at first.
The fatality ratio is 90% at 0% antibiotics coverage of the population and 15% at 100% antibiotics coverage of the population. Assume for the sake of simplicity that those belonging to the recovering population do not pose any threat of infection, either because they are really quarantined or because they are not contagious any more.
Preguntas del caso:
2.1. Desarrolla el diagrama de flujo del caso (5 puntos, producto: diagrama de flujo)
2.2. Construye el modelo de dinámica de sistemas basado en R y simula el modelo por un periodo de 1 mes.(5 puntos, productos: hipótesis dinámica y gráfico que la respalde)
2.3. Grafica y comenta la evolución de infections, deaths, recovering population y deceased population (5 puntos, producto: gráficos de evolución y comentarios del comportamiento)
2.4. Suponga ahora que la antibiotics coverage of the population es del 100%. Compara la evolución de de infections, deaths, recovering population y deceased population con las obtenidas en la pregunta anterior. (5 puntos, productos: código en R, gráficas y comentarios comparando ambos modelos)
Introducción:
After following this SD course, you decide to start working as a model-based business analyst. Your first job consists in helping out the manager of a luxury car company that produces hand-made sports cars. The company faces severe inventory, production and workforce fluctuations following sales fluctuations. The manager wants you to make a model to understand the interactions between production, inventory and workforce in order to be able to reduce these fluctuations.
Descripción del caso:
Modelando la estructura de una firma
Smart as you are, you decide to make, first of all, a model in equilibrium with constant sales of 100 cars per month. These sales empty the stock of inventory. The inventory initially consists of 300 cars and is replenished by a production inflow which equals the size of the workforce (i.e. the employees) times the productivity of an average worker. The average productivity is currently 1 car per person per month.
The target inventory currently equals the sales times an inventory coverage of 3 months. This target inventory is used to calculate the inventory correction which is used to calculate the target production. The inventory correction is calculated as: ( target inventory - inventory ) / time to correct inventory. The time to correct inventory is currently 2 months. The target production is then the sales plus the inventory correction.
The target production divided by the productivity of the average worker results in the target workforce. The discrepancy between the target workforce and the actual workforce currently drives the ‘hiring and firing’ strategy of the company as follows: net hire rate = ( target workforce - workforce ) / time to adjust workforce of 10 months. The workforce could be modeled as a stock variable regulated by the net hire rate. Since you will start out from equilibrium, you could take the target workforce as the initial value of the workforce.
Preguntas Iniciales del caso
3.1. Construye un modelo de dinámica de sistemas basado en el caso anterior, simula el modelo por un periodo de 100 meses. Asegúrate que el modelo este en equilibro (2 puntos, productos: modelo en R, envía tu modelo con la versión final de tu tarea, emplea el siguiente formato para nombrar tu modelo: TuNombre_cadena_suministro.R)
3.2. Ahora corre el modelo con especificando haciendo que la variable sales cambie de 100 a car per month a 150 cars per month. Muestra y describe el comportamiento del modelo para las siguientes variables: sales, inventory y workforce (3 puntos, productos: gráficos describiendo el comportamiento del sistema, comentarios que describan el comportamiento del sistema).
3.3. ¿Cuánto tiempo toma para que el sistema vuelva al equilibrio dinámico? (5 puntos, productos: gráfico con anotaciones describiendo el tiempo que tarda el sistema en volver al equilibrio).
3.4. Construye el diagrama de fase del sistema y describe el comportamiento esperado empleando este diagrama de fase (5 puntos, productos: diagrama de fase y explicación de comportamiento).
Modelando la estructura de la cadena de suministro
Now, suppose that the company you work for is part of a supply chain consisting of 3 manufacturing companies, all three with the (same) structure developed in the first part. In fact, you are working for the assembler who sells the final product to the final customers. This assembler is supplied by a tier one supplier, and the tier one supplier is supplied by the tier 2 supplier. The tier 2 supplier faces extremely undesirable oscillations in demand and production.
Preguntas adicionales del caso
3.5. Asume que la producción del ensamblador (i.e. assembler) constituye la demanda de la firma en el primer nivel de suministro (i.e. tier 1 supplier), y que la producción de la firma en la primera línea de suministro constituye la demanda de la firma en el segundo nivel de suministro (i.e. tier 2 supplier). Expande tu modelo original, asume que la estructura intérnate de estas firmas adicionales es idéntica a la estructura de la firma ensambladora (5 puntos, productos: modelo en R, envía tu modelo con la versión final de tu tarea, emplea el siguiente formato para nombrar tu modelo: TuNombre_cadena_suministro_completo.R).
3.6. Describe la dinámica de comportamiento que resulta de integrar estas nuevas firmas al modelo para las siguientes variables: sales, inventory y workforce (5 puntos, productos: gráficos describiendo el comportamiento del sistema para las tres firmas, comentarios que describan el comportamiento del sistema).
3.7. Describe e implementa una política que ayude a disminuir la inestabilidad de la cadena de suministro. Compara en un mismo gráfico el comportamiento del sistema con y sin política (5 puntos, productos: gráficos describiendo el comportamiento del sistema para las tres firmas con y sin política, comentarios que describan el comportamiento del sistema).
Introducción:
The next few decades will be characterized by further urbanization. Part of it will –especially in Asia and Africa– be caused by so-called ‘New Towns’. The concept of ‘New Town’ is used for a particular type of urban development: a more or less independent new town relatively distant from existing cities. New urban developments within existing (older) urban areas (New Town in Town) or large urban extensions to the edges of the major cities is generally referred to as urban renewal, not as New Towns. The New Town concept is not new. Worldwide, there are hundreds of new towns (Brasilia, Chicago, San Francisco, Milton Keynes, many Eastern European, Russian, South American, Chinese, Korean and French cities) and many new ones are under construction (especially in Asia and Africa). Although the number of inhabitants of these cities varies from less than 50000 to more than a million, and although they are very different in design and function, there are interesting dynamic parallels and the same ‘mistakes’ –in spite of good examples like Detroit– are being made over and over again. One of the SD classics –Urban Dynamics by Jay W. Forrester (1969)– shows that SD is an appropriate method to help to understand New Town structures and dynamics and to test policies to solve undesirable evolutions. Suppose that you are hired as an adviser-modeler by a few rising new towns to test policies to solve the ‘root causes’ of undesirable dynamics. Since you are following this SD course, you decide to make and subsequently use a SD model. Use the information below, which is based on a modified version of George Richardson’s URBAN1 model.
Descripción del caso:
The population
The size of the population of a new town changes through immigration, births, emigration, and deaths. Suppose that the new town you are about to model already has 50000 inhabitants, and has a birth rate of 3%, and a death rate of 1.5%. And suppose that there is constant emigration with a normal emigration rate of 7% per year. Immigration could be modeled as the product of the current population, the normal immigration rate, the job availability multiplier for immigration, and the housing availability multiplier for immigration. This housing availability multiplier for immigration is a function of the households to houses ratio: suppose that if the households to houses ratio equals 1, the multiplier equals 1, that if the households to houses ratio equals 1.5, the multiplier equals 0.25, that if the households to houses ratio equals 2, the multiplier equals 0, that if the households to houses ratio equals 0, the multiplier equals 1.4, and that if the households to houses ratio equals 0.5, the multiplier equals 1.3. The number of households depends on the size of the population and the average size of households, in that part of the world still 4. Suppose that the normal immigration rate equals 10%.
Houses
The number of houses, initially equal to 14000, increases by means of construction of houses and decreases through demolition of houses. The average demolition rate of houses (without additional policies) equals 1.5% per year. The construction of houses could be modeled as a 3rd order delay (delayed with 2 years) of the product of the land availability multiplier for houses, the housing scarcity multiplier, the number of houses, and the construction rate of houses of 7% per year. The housing scarcity multiplier is a function of the households to houses ratio connecting following points (0, 0.2), (0.5, 0.3), (1, 1), (1.5, 1.7), and (2, 2). The land availability multiplier for houses is a function of the land fraction occupied: for a land fraction occupied of 0% the multiplier equals 0.4, for a land fraction occupied of 25% the multiplier equals 1, for a land fraction occupied of 50% the multiplier equals 1.5, for a land fraction occupied of 75% the multiplier equals 1, and for a land fraction occupied of 100% the multiplier equals 0. The land fraction occupied corresponds to the sum of the land use of all businesses and the land use of all houses, divided by the total area. Suppose that the useful total area of the new town is 5000 hectare, that the amount of land per house is 0.05 hectare, and that the amount of land per business (i.e. for each business structure) is 0.1 hectare.
Businesses and labor force
The number of businesses (i.e. business structures), initially 1000 business, increases through construction of business structures and decreases through demolition of business structures with an average demolition rate of business structures of 2.5% per year.
Construction of business structures could be modeled as the product of the land availability multiplier for business structures, the business labor force multiplier, the number of businesses, and the construction rate of business structures of 7% per year.
This land availability multiplier for business structures is a function of the land fraction occupied: the multiplier is of course 0 for 100% of the land fraction occupied, it equals 1 for 0% of the land fraction occupied, and it equals 1.5 for 50% of the land fraction occupied. The business labor force multiplier is a function of the labor force to jobs ratio connecting (0, 0.2), (0.5, 0.3), (1, 1), (1.5, 1.7), and (2, 2). The aforementioned job availability multiplier for immigration is also a function of the labor force to jobs ratio connecting following points (0, 2), (0.5, 1.75), (1, 1), (1.5, 0.25), and (2, 0.1). This labor force to jobs ratio depends of course on (i) the size of the labor force which equals the product of the population and the labor force to population ratio of 35%, and of (ii) the number of jobs which equals the number of businesses times the initial number of jobs per business structure which amounts to 18 FTEs. Model following two key performance indicators too: the unemployment ratio and the housing vacancy ratio. Both are per definition between 0 and 100%.
Preguntas del caso:
4.1. Construye un modelo de dinámica de sistemas basado en el caso anterior, simula el modelo por un período de 200 meses (5 puntos, productos: modelo en R)
4.2. Realiza gráficos de la evolución de las empresas, las viviendas y la población y de los efectos de éstos en la tasa de desempleo (unemployment ratio) y la tasa de viviendas vacías (housing vacancy ratio). ¿Qué problemas puedes derivar de estos gráficos? (5 puntos, productos: gráficos y comentarios del comportamiento)
4.3. Forrester’s Urban Dynamics shows that additional demolition of empty bad quality housing in case of high housing vacancy ratios and rezoning could prevent urban decay to kick in or worsen. Thus add a variable additional demolition rate to demolish beyond normal demolishing above a 10% housing vacancy ratio. Let the additional demolition rate increase linearly from 0% per year for a 10% vacancy ratio to 5% per year for a 15% vacancy ratio, and linearly from 5% per year for a 15% vacancy ratio to 50% per year for a 100% housing vacancy ratio. Add this additional effect to the demolition of houses too (30 puntos, producto: modelo actualizado en R [10 puntos], gráficos [10 puntos] y conclusiones del comportamiento de las variables y el sistema [10 puntos])