Friday, February 28, 2014

Overview and Challenges of Bogotá’s Transmilenio

Transmilenio was a revolutionary bus rapid transit (BRT) system in Bogotá, Colombia. Launch in 2000, it aimed to mimic the speed of a Metro in facilitating movement of people, but at a fraction of the capital cost. Despite its international acclaim and other cities trying to emulate the system, Transmilenio is not without its share of controversies and challenges. In the paper Bus Rapid Transit: Is Transmilenio a Miracle Cure? Alan Gilbert of University College London explores the background of the system and what crucial actions are necessary for Transmilenio to sustain its core missions of facilitating transportation, maintaining the general interests of poor people, and bringing public and private sectors together to “share responsibilities for the delivery of the service.”

Management was a huge issue in the old traditional bus system, where the various bus companies tried to obtain licenses to operate in the most profitable routes, leading to too many buses at the city center and too few in the outskirts. The competitive nature of the system meant poor bus maintenance and little regard for the well-being of other road users or the passengers. Transmilenio was born out of a desire to modernize the transportation infrastructure without paying the hefty amounts for a Metro. While the concept of BRT isn’t new, Transmilenio was revolutionary for its expansive network and high accolade during the first few years of operation. With dedicated bus lanes and quick loading time, a 2001 survey gave Transmilenio a rating of 4.64 out of 5, with general consensus of saved time and city’s improved cohesion.

Yet criticisms were inevitable, from decay of roads to overcrowding and eventual fare hike. One issue is that a trip on Transmilenio is more expensive than one on traditional bus. This is most pressing for the poorest, and together with overcrowding, has led to slow growth in passenger count. The central agency of Transmilenio, which receives no operating subsidy, has complained about the “unfair competition” from the traditional bus. Gilbert proposes that one solution is to reduce the number of old buses. Scrapping of old buses, in exchange for the license to run new buses, has been remarkably slow though, and many illegal “pirate” buses are still in operation. This is the core of Gilbert’s message that while Transmilenio is a great concept, “complementary changes have to be made in the rest of the sector” if the system is to be sustainable for the future, for Transmilenio by itself cannot solve the city’s transportation challenges.

  • Alan Gilbert: “Bus Rapid Transit: Is Transmilenio a Miracle Cure?"

Broadacre City

Broadacre City is a city layout concept developed by Frank Lloyd Wright, who was an influential American architect in the first half of the 20th century. Wright was largely ambivalent about dense cities. While he worked on some of the most important building in New York City, such as the Guggenheim Museum, he also envisioned that dense cities were obsolete given the advancement in technologies, most notably automobiles and telephones. His concept of Broadacre City would give each family one acre of land in the countryside. In 1935, Wright unveiled his detailed plan on a 12 ft x 12 ft model representing a community. It was ironically presented at New York’s Rockefeller Center, the antithesis of what Broadacre City called for.

Proposed during the Great Depression, Broadacre City reflected the social and economic uncertainty facing the country at the time. In his 1932 book The Disappearing City, Wright wrote of the “comfort” of wide spaces and that people of the future “will have all forms of production, distribution, self improvement, enjoyment, within a radius of a hundred and fifty miles of his home now easily and speedily available by means of his car or plane.”Wright’s Broadacre City called for pockets of community centers or small manufacturing centers, which were all necessities for society, but they would all be spread out. Roads would be the crucial artery linking the decentralized settlement. Inter-dispersed throughout the community would be single-family homes. Some of Wright’s ideas ultimately took shape in the form of the suburban sprawl observed in the United States after World War II, and for that reason Wright is aptly labeled as the prophet of suburbia. But it was the organized and planned nature of the development that separated Broadacre City and actual developments.

Even during the initial release in the 1930s, Wright faced much criticism for his Broadacre City layout proposal. Even before the days of environmentalism that have since followed, people back then called his plan largely wasteful. Today, many urban centers are seeking to reverse the effects of suburban sprawl that took effect in much of the country in the latter half of 20th century. While Wright’s original model had called for “No traffic problems” thanks to the decentralization of the city, ironically one of the most negative consequence of the suburban sprawl has been traffic congestion and environmental degradation.


Monday, February 24, 2014

Air Pollution in Mexico City

The papers Quantification of Local and Global Benefits from Air Pollution Control in Mexico City, Improving Air Quality in Megacities: Mexico City Case Study, and Air Quality Management in Mexico all looked into the issue of air pollution in the Mexico City Metropolitan Area, which increased its population 6-fold from 1950 to 2000, and presently is the largest urban agglomeration in the Western Hemisphere with population of more than 20 million While population affects many burgeoning cities in developing cities, it is especially problematic for Mexico City, which consumes more than 40 million liters of fuel daily, due to the surrounding topography, as mountains and frequent thermal inversions help to trap pollutants within the Valley of Mexico, which the capital sits. Since the mid-1980s, the government and citizens have recognized the serious concern of pollution, and regulations implemented in the 90s have helped to reduce the concentrations of various pollutants.

Currently transportation is the major source of pollution in the city, and one of the problems is that high-occupancy modes of transit have been declining as minibuses have gained popularity for their superior service and convenience, while existing formal high-occupancy systems, including the Metro, have not adequately adapted to the growing population trends. Antiquated fleet also contributes significantly to pollution, as the concentration of economic activities bring in much freight traffic. Regulation efforts have been put in to mitigate pollution. Vehicle inspection and maintenance programs, including no-driving days, began to be enforced, limiting the use of cars by one weekday starting in 1989. The policy has been remodeled to assign the ban depending on the vehicle’s emission levels. The country has also issued air quality standards comparable to those in United States. Natural gas began to replace fuel oil, and fuel quality has also been improved to reduce sulfur content and introduce unleaded gasoline. Furthermore, a low-interest loans to substitute old taxis have been implemented to improve fuel efficiency.

Despite the progresses, there are still potential pollution-mitigating projects with promising cost-benefit analysis from the standpoint of capital investment costs versus the decreased cost of health deteriorations. The project includes taxi fleet renovation, Metro expansion, hybrid bus introduction, liquid petroleum gas (LPG) leak prevention, and electricity cogeneration. The study finds that if all were implemented, the measures could save 100 lives, over 500,000 cases of minor restricted activity days (MRAD), and amount to $150 million (US) of local benefits per year. In particular, fuel savings would offset the cost of investment costs of taxi renovation, making this a particularly attractive economic investment. On the other hand, preventing LPG leaks would produce the greatest health benefit, compared to its size of investment costs, making this a high priority.

  • Instituto Nacional de Ecología: “Quantification of Local and Global Benefits from Air Pollution Control in Mexico City”
  • L. Molina and M. Molina: “Improving Air Quality in Megacities: Mexico City Case Study”
  • Adrián Fernández-Bremauntz: “Air Quality Management in Mexico”

Tuesday, February 18, 2014

Internal Combustion Engine

The engine of an automobile burns gasoline. The combustion produces expanding gases, which create the mechanical power used to move the vehicle. Generally speaking, the combustion can take place inside the engine, in the case of an internal combustion engine, or outside for an external combustion engine. Steam engine is an example of the latter. But internal combustion engine is more efficient, and is the type found in most automobiles.

The challenge of the engine is to sustain the transfer the energy from gasoline to kinetic energy of the vehicle. This repetitive mechanism is accomplished through the four-stroke combustion cycle, also known as the Otto cycle. Inside the cylinder of the engine is the piston, and its movement will direct the flow of the cycle. During the first step, known as the intake stroke, air and gasoline enters the engine, as the down movement of the piston opens up the intake valve, in order for the components to enter. Secondly, the upward movement of the piston then compresses this mixture of gasoline and gas. However, a mere compression does not start the reaction. During the third step, as the piston reaches the peak of its stroke, the spark plug gives off a spark that provides the activation energy necessary to finally ignite the gasoline. Finally, as the piston moves downward again, exhaust from the combustion leaves though a different value. While the movement of the piston is linear, it is helps to move the crankshaft, which is connected to the piston via the connecting rod. The rotational movement of the crankshaft is important, since it is then connected by gearing to the wheels of the automobile, which ultimately move in a rotational manner.

Various factors can go wrong in the engine, and tracing the steps of the Otto cycle reveals some of the reasons. To start off, the ingredients can be bad. The gasoline needs to have little impurity, such that it can burn. At the same time, the necessary amount of air is needed to supply enough oxygen for the combustion reaction. Once inside, lack of compression of spark also can be a source of problems. Compression can fail with leaky cylinders or valves not sealing properly, both of which prevents the pressure buildup from occurring. As for the spark, the wiring may be worn out or damaged.


Tuesday, February 11, 2014

Risk Taking

Encountering uncertainty and managing risk is as fundamental as life itself. After all, aside from birth and death, little about life is certain. Understanding uncertainty and risk is relevant in various fields from study, from psychological counseling to investment undertaking. In an engineering context, it is important to understand the psychology behind decision making that affects the processes of capital projects, and their outcome as the projects come to fruition and enter usage.

It turns out that risk-seeking is somewhat hardwired in the brain. The neurological structure controls the actions of humans. Within the brain, the region of particular interest is the amygdala. Located within the temporal lobe of the brain, it is the center of emotion processing. It helps to configure emotional responses by storing memories, and recollections in turn help to determine the type of response elicited in new situations. Personality is largely determined by one’s reactions to various events, and not surprisingly, the amygdala plays a crucial role in shaping personalities. Scientific research has shown that people with damaged amygdala tend to exhibit a lack of fear and conscious. It also turns out that aside from neurology, evolution also plays an important role in risk. Historically men have been more risk-taking than women. Partial explanation comes from the historical fact that during human evolution, competition for social status and resources was predominantly focused among the males.

To the ordinary, risk takers are more inclined to engage in “dangerous” activities and gain more excitement from completing them. But research shows that they may suffer from boredom and lower job satisfaction. Constrained by the limits of society they reside in, they may also "have a hard time deriving meaning and purpose from everyday life." It is also consequential to recognize that more developed regions tend to foster more of these behaviors. For one, many of these risky activities, from skydiving to mountaineering, are not inexpensive hobbies. Secondly, for more developing societies, more efforts are needed to simply sustain some of the basic necessities, leaving out many opportunities to seek out additional challenges. As a result, a cultural irony develops in that as societies develop more and establish better and sustainably certain living conditions for the people, the more likely it is to indirectly foster uncertainty and risk-seeking.


Wednesday, January 29, 2014

Silla Exhibit at The Met

The Metropolitan Museum of Art currently has an exhibit on Silla, the Korean kingdom from 57 B.C. to 935 A.D. The exhibit runs through February 23rd and features excavated objects dating back to the kingdom from years 400 - 800, much of which deals with gold, as Silla was "renowned as a country of gold." The exhibit and the objects illustrate trade and interaction with rest of Eurasia via the Silk Road as a main theme of the kingdom.

This dagger and sheath has its form traced to Central Asia, where similar types have been found. It presumably reached Korea as a "diplomatic gift or a trade item."

Buddhism was also introduced to Silla from its early founding in Indian subcontinent. Construction of great numbers of Buddha statues illustrates the religion's significance in the kingdom.


Thursday, January 23, 2014

Quick Look at IBM and Lenovo

It was reported this week that IBM will sell its x86 division to Lenovo for $2.3 billion. This came after IBM reported its seventh straight quarter of declining revenue, at $27.7 billion for Q4-2013. Details show that Software, Services and Global Financing divisions each grew, but Systems and Technology was the worst-performing division, declining in revenue by 26.1%. The deal with Lenovo allows IBM to offload the low-end server business. The x86 business is "the generic name for Intel processors released after the original 8086 processor."

This isn't the first deal between IBM and Lenovo. In 2005, Lenovo purchased IBM's PC business, and later acquisitions propelled Lenovo to be world's top PC company last year. While IBM had a disappointing 2013, being the only company in Dow Jones to decrease, Lenovo posted record-high revenue and profit in its latest quarterly financials released in November. Notebooks consisted over half of Lenovo's revenue, and its industry outlook cites that "customers no longer see Tablet as PC replacement."


Friday, November 29, 2013

VBA Simulation of Shuffling and Distributing a Deck of Cards

Here's a simple VBA program that simulates shuffling and distributing a standard deck of 52 cards to 4 players. The program outputs the results in cells A1 through D13 of the current Excel spreadsheet, with the 4 rows corresponding to the 4 players' cards.
Sub ShuffleCards()
'This program simulates shuffling of a standard deck of 52 cards to 4 players
'Results are outputted in 4 columns in cells A1:D13

'H: heart, S: spades, D: diamod, C: club
'2 thru 10, J for jack, Q for queen, K for king, A for ace
'2H would be 2 of hearts, KD would be king of diamonds, etc.

suits = Array("H", "S", "D", "C")
num = Array("2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A")

Dim cards(0 To 51) As String
For i = 0 To 3
For j = 0 To 12
cards(13 * i + j) = num(j) & suits(i)
Next j
Next i

For i = 1 To 1000
c1 = Int(52 * Rnd)
c2 = Int(52 * Rnd)
temp = cards(c1)
cards(c1) = cards(c2)
cards(c2) = temp
Next i
For k = 0 To 51
Cells(k Mod 13 + 1, Int(k / 13) + 1) = cards(k)
Next k
End Sub

The shuffling algorithm is to run through 1000 iterations of swapping two randomly chosen cards.

Sunday, November 24, 2013

“Comments on the Interpretations of Game Theory” Digest

In the paper “Comments on the Interpretations of Game Theory,” published in Volume 59, Issue 4 of Econometrica in July 1991, Ariel Rubinstein discusses notions of game theory and strategy that aims to highlight some of the inconsistency between the interpretation and application. Rubinstein argues that equilibrium strategy describes not only a player’s plan of action, but also the considerations that support the optimality of the plans. The paper also argues that models should encompass the perception of a real life situation by the decision makers. Game theory, as Rubinstein writes, is not simply about abstract mathematics but about the real world.

The first half of the paper deals with the notion of strategy. Rubinstein argues that the conventional interpretation is inconsistent with the way it is applied, leading to confusion. In one of the contexts, Rubinstein talks about extensive games with more than one moves. In the game, a player’s strategy is required to specify an action for each node in the game tree corresponding to that player’s movement. However, the incongruence comes when an action must be specified, even after earlier moves that would make the subsequent decision point inconsistent with the earlier moves. The necessity of this specification stems from the need to determine subgame-perfect equilibrium to test the rationality of the plans. In all, a strategy needs to encompass not only the player’s plan, but also the opponents’ belief in the chance that the plan was not followed.

Rubinstein also looks at the interpretation of strategy in mixed strategies. While intuitively problematic, there are clear cases in which players choose random actions, preferring over pure strategies. One interpretation of mixed strategy is to use a large population and having each occurrence take a random draw of the items from the population. Another interpretation is the purification idea, whereby a mixed strategy is dependent on private information not specified in the model. This interpretation argues that ostensibly random behaviors are actually deterministic. Finally, Rubinstein looks at the case of limited memory, which helps to keep modes of behavior simple. When probabilistic nature of doubt is introduced, there may be additional decision points that are unreachable, but added to the game form merely to allow the discussion of reasoning in the state of doubt.

From these discussions, Rubinstein tries to adopt the view that a game is not “a rigid description of the physical rules of the world,” but instead a “comprehensive description of the relevant factors involved in a specific situation as perceived by the players.” Towards that idea, model should include only the factors perceived by the players to be relevant, making the application of game theory “more of an art than a mechanical algorithm.” Finally, Rubinstein talks about regularity, which is necessary for employing game theory as a descriptive science. Game theory, in conclusion, builds models from intuition and from mathematical knowledge uses deductive arguments, which can’t discover the truth alone. Instead, game theory also deals with psychological elements, which help to distinguish humans from machines, which Rubinstein believes is “more exciting and certainly more meaningful.”

Monday, November 18, 2013

San Diego - Tijuana Border and Flight Comparison

A proposed solution to San Diego's crowded airport is to build a pedestrian bridge to Mexico. Tijuana's General Abelardo L. Rodriguez International Airport (TIJ) is located just across the US-Mexico border, and the proposed bridge, about 20 miles away from downtown San Diego, would allow people to cross the border into the airport. Otay-Tijuana Venture, the project's developer, cites that of the "roughly 4 million people who fly into and out of TIJ each year, more than half cross the border one way or the other." However, crossing the San Diego - Tijuana borders on automobile involves notoriously long waiting times. Some prefer to cross by foot and then catch transportation on the other side. San Ysidro crossing between the two cities is the world's busiest port of entry.

How much cheaper is it to fly out of Tijuana instead of the San Diego area airports? The following are the costs of the cheapest flights, for one adult roundtrip, from Expedia retrieved tonight, departing on Monday, December 7th and returning Wednesday, December 9th:

Destination San Diego Tijuana
New York $351.10 $972.59
London $2,214.60 $2,282.60
Tokyo $1,050.50 $3,932.80
Sydney $1,577.80 $3,082.21
Cairo $1,316.68 $3,930.00
Rio de Janeiro $1,269.49 $1,540.55
Panama City $800.40 $938.19
Mexico City $342.59 $291.16
Cancun $400.40 $371.04

For many of these cities, San Diego offers an enormous discount. Even for other Latin American destinations, San Diego offers cost advantage. It is only within Mexico that Tijuana offers cost advantages. The Tijuana flights to rest of Mexico are also more frequent and have fewer stops on average. Looking at just these results then, it would seem as though the pedestrian bridge serves to relieve those in Southern California traveling to various parts of Mexico by air. A positive externality would be slight relieving of the border crossing for those going to the airport.