Show of 09-15-2018

Tech Talk

September 15, 2018

Email and Forum Questions

  • Email from Richard in Rockville: Hello Richard and Jim. On the August 11, 2018 show, you discussed a building that was not located correctly on a map. The location accuracy of a symbol on many (or most?) maps intended for display on the internet is determined by the symbol’s Latitude and Longitude location values, which are expressed in Degrees (360), Minutes(60), and Seconds(60). Resolution and accuracy are generally limited since only the whole number value of seconds is used. Given the earth’s geometry, Latitude/Longitude values differing by One Second are about 100 feet apart. I hope that the above information might address the “building in the wrong spot” concerns expressed on a recent Tech Talk show. Thank you Richard and Jim for your interesting Saturday morning shows on WFED, Richard in Rockville
  • Tech Talk Responds: Thanks for the feedback. Accuracy in maps in becoming a bigger issue as we rely on GPS systems for more things. Hopefully the stored accuracy will improve beyond what you have referenced in your comment. I think my cell phone has pretty accurate tracking. It is giving Latitude and Longitude to six decimal places. Not bad.
  • Email from Anna in Kilmarnock: I recently created a user manual and distributed it as a PDF.he PDF so so large that it is difficult to email. How can I compress this P DF for easier distribution? Love the podcast. Anna in Kilmarnock, VA
  • Tech Talk Responds: First of all, I would not distribute a large file via email. I would upload to the cloud and share the link to the stored version. You can do this easily with Dropbox, Box Google Drive, Microsoft OneDrive, etc. I use my Dropbox account for such sharing.
  • Fortunately, you can easily compress to PDF and easily reduce its size by 50%. The actual compression depends on the number of images in the file.
  • Windows does not handle PDFs by default, so in order to open and compress a file, you must download some third-party software. Free PDF Compressor is a good option. It offers a variety of compression qualities from which to choose.
  • Mac users can use the built-in Preview app to compress PDFs without having to download any third-party applications. First, open your file in Preview by selecting the file in Finder, hitting Space, and then clicking the “Open with Preview” button. In the export window, select the “Reduce File Size” option from the “Quartz-Filter” drop-down menu and then click the “Save” button.
  • You can also use an online compression tool. SmallPDF is easy and fast. Your file is also deleted from their servers after an hour.
  • Email from Tom Shum: Dear Doc and Jim. I think you may have made a mistake regarding the space elevator. Below geosynchronous orbit, a tether tied to the earth will simply collapse. If a tether is tied to a geosynchronous satellite, it will simply collapse because the weight of the tether will pull the satellite out of orbit. The center of mass of the elevator (tether plus support satellite) must be at or above geosynchronous orbit. If it is above geosynchronous orbit, centrifugal force will keep it vertical. The further above geosynchronous orbit, the greater will be the centrifugal force. The centrifugal force must be great enough to support the tether and the payload. Tom Schum
  • Tech Talk Responds: You are correct. Two forces must be considered. Gravitational force pulls the satellite towards the Earth. Centrifugal force pulls it away from the Earth. A geosynchronous orbit, where the two forces are equal is 26,199 miles high. In order for the centrifugal force to hold up a payload, plus cable, it must be greater than the gravitational force. This requires that the satellite be higher than geosynchronous orbit. It must be between 60,000 miles and 200,000 miles above the earth, depending on the payload. Thank you for your correction.
  • Email from Dave in Chantilly: Dear Doc and I Jim. I have heard you talk about robots in the past. What programmable robot should I buy for my grandkids? Christmas is coming up and I want to get them something educational. Love the show. Dave in Chantilly
  • Tech Talk Responds: Programmable robot kits for kids are a great way to introduce your children to Science, Technology, Engineering, and Math (STEM).
  • Working with these robotic kits can foster a sense of accomplishment, and inspire the mind as kids work out new ways to program the robots to perform a task.
  • Here a couple that I like
    • Lego Mindstorms EV3 ($349) — LEGO MINDSTORMS has been the leader in programmable robot kits for quite a while. Combining all of the available LEGO brick types with the EV3 brick, which contains an ARM9 processor and input and output ports, along with a sufficiently large collection of sensors, motors, and other components, allows you to build 17 LEGO-designed robotic creatures. No soldering is required, and programming your creations is performed with a drag-and-drop programming language.
    • Makeblock mBot Ranger ($149) — The mBot Ranger is a STEM educational robot designed to help children explore and learn about robotics. The mBot Ranger makes use of precision metal components and a pre-assembled Arduino controller board to build three different robots; Land Raider, a tank-like rover; Nervous Bird; a two-wheeled self-balancing robot; and Dashing Raptor, a three-wheeled racer. The mBot Ranger can be programmed using Scratch, a graphical programming language that allows you to build up complex programs by dragging programming blocks into place.
  • Email from Jay in Kilmarnock, VA: Dear Doc and Jim. Why type of weather app do you use to keep track of the weather when you are on the water. I want to have something that is quick, easy to view, and provides notfications.
  • Tech Talk Responds: My favorite is the Storm Radar app by the Weather Company. You get a choice of one of three map styles; black background with roads and major landmarks, map, or satellite photo. Once you have selected one of the three, you can always go back and change the setting to one of the other map types.
  • The app then shows how radar colors correspond to what’s happening weather-wise. Shades of green indicate light rain, yellow and red indicate heavy rain, blue is snow. After either selecting your current location or searching for another location, a map is displayed. At the top the map is a listing of the current weather and forecast; a tap opens a window for additional details.
  • The most important part of the app is the animated radar map. It covers the past two hours of actual weather, the current weather situation, and then the forecasted map for the next six hours. This radar map loops, or can be paused with a tap. Users can switch layers on the map. Radar is the default layer, but it’s also possible to look at wind, temperature, or even tropical storms.
  • Email from Ngoc in Ohio: Dear Doc and Jim. I have recently heard quite a bit about TinyURLs as a way to trick people during a Phishing attack. What exactly are TinyURLs? The whole thing seems confusing to me. Love the show. Ngoc in Ohio.
  • Tech Talk Responds: TinyURL is a URL shortening web service, which provides short aliases for redirection of long URLs. It web address is: http://tinyurl.com/. Kevin Gilbertson, a web developer, launched the service in January 2002 so he would be able to post links in newsgroup postings which frequently had long, cumbersome addresses.
  • The TinyURL homepage includes a form which is used to submit a long URL for shortening. For each URL entered, the server adds a new alias in its hashed database and returns a short URL such as http://tinyurl.com/2unsh in the following page. If the URL has already been requested, TinyURL will return the existing alias rather than create a duplicate entry. The short URL forwards users to the long URL.
  • Short URL aliases are seen as useful because they are easier to write down, remember or pass around, are less error-prone to write, and also fit where space is limited such as IRC channel topics, email signatures, microblogs. People posting on Twitter make extensive use of shortened URLs to keep their tweets within the service-imposed 140 character limit.
  • Starting in 2008, TinyURL allows users to create custom, more meaningful aliases. This means that a user can create descriptive URLs rather than a randomly generated address. This is the service the phishers are using to trick unsuspecting targets.

Profiles in IT: Vilhelm Friman Koren Bjerknes

  • Vilhelm Bjerknes was a Norwegian physicist and meteorologist who did much to found the modern practice of weather forecasting.
  • Vilhelm Bjerknes was born March 14, 1862 in Christiania, Norway.
  • Bjerknes enjoyed an early exposure to fluid dynamics, as assistant to his father, Carl Anton Bjerknes, who had discovered by mathematical analysis of actions between pulsating and oscillating bodies in a fluid.
  • Vilhelm Bjerknes became assistant to Heinrich Hertz in Bonn and made substantial contributions to Hertz’ work on electromagnetic resonance.
  • He proved experimentally the influence which the conductivity and the magnetic properties of the metallic conductors exert upon the electric oscillations, and measured the depth to which the electric oscillations penetrate metals (skin effect).
  • In 1895 he furnished a complete theory of electric resonance. These methods contributed much to the development of wireless telegraphy.
  • In 1895, he became professor of applied mechanics and mathematical physics at the University of Stockholm.
  • He elucidated the fundamental interaction between fluid dynamics and thermodynamics, with his major contribution being equations used in climate models.
  • His work that inspired others to apply it to large-scale motions in the oceans and atmosphere and to make modern weather forecasting feasible.
  • Bjerknes himself had foreseen the possible applications as early as 1904. His work was supported by the Carnegie Institution, of which he became a research associate.
  • Statics and Kinematics and Dynamic Meteorology and Hydrography, were published in 1913. These formed the basis of modern weather prediction.
  • In 1906, Bjerknes was the first to describe and mathematically derive translational forces on bubbles in an acoustic field, now known as Bjerknes forces.
  • In 1907, Bjerknes returned to the Royal Frederick University in Oslo before becoming professor of geophysics at the University of Leipzig in 1912.
  • In 1917, he founded the Geophysical Institute, University of Bergen where he wrote his book On the Dynamics of the Circular Vortex with Applications to the Atmosphere and to Atmospheric Vortex and Wave Motion (1921), and laid the foundation for the Bergen School of Meteorology.
  • He was the originator there of an improved and more scientific weather service, afterwards controlled by his son and collaborator, the meteorologist Jacob Bjerknes,
  • From 1926 to his retirement in 1932 he held a position at the University of Oslo.
  • He was elected a member of the Royal Swedish Academy of Sciences in 1905 and of the Pontifical Academy of Sciences in 1936 and a Fellow of the Royal Society.
  • He died in Oslo on April 9, 1951, of heart congestive heart failure.
  • The craters Bjerknes on the Moon and Bjerknes on Mars are named in his honor.

First Ride on the Bird Electric Scooter

  • Easy to locate with GPS system in app
  • First time required a driver’s license scan
  • First time required reading and agreeing to terms of use
  • Starting the scooter manually by pushing with one leg
  • Then hit the accelerator and speed up to 15 MPH, which is too fast for the sidewalk and too slow for the road.
  • Lock the scooter after riding is easy, but a picture of the scooter must be taken.
  • Overall a good experience.

The Physics the Powers Hurricanes

  • Scientists have long known that hurricanes that hit the Atlantic coasts of North and Central America are born in storm systems off the west coast of northern Africa.
  • These wettest of storms are driven by weather over one of Earth’s driest of places, the Sahara (the name means desert in Arabic).
  • These small turbulence travel from east to west in the jet stream.
  • Hurricanes form near the equator over warm ocean waters. The term hurricane is used only for the large storms that form over the Atlantic Ocean or eastern Pacific Ocean.
  • The generic, scientific term for these storms, wherever they occur, is tropical cyclone.
  • Hurricanes are among the most powerful of all natural phenomena. They get their power from the condensation water.
  • The latent heat of vaporization of water is 2.256 MJ/kg. That is, it takes 2.256 million Joules of energy to boil one kilogram of water.
  • Of course, the reverse is also true. When one kilogram of water condenses, 2.256 million joules of energy become available.
  • The necessary ingredients for a stable hurricane are
    • A large area of warm ocean water (preferably at least 27 C).
    • Latitude of at least 5 degrees (North or South)
    • Vertical instability (low pressure at sea level is a good choice).
    • Minimal vertical wind shear (no jet steams please!).
  • Of these conditions, the first provides the energy, the rest allow the storm to get organized into a self sustaining pattern that concentrates the energy.
  • First, air rushes in to fill the low pressure region (item 4 above). As the air moves in, moisture in the air condenses and releases energy, which in turn warms the air reducing its density. This warm air rises, pulling more air in from around the outside.
  • All of this air rushing in towards the center is subject to a phenomenon called the Coriolis Force, that occurs due to the motion of the Earth. Overall, the storm picks up a counterclockwise rotation in the Northern Hemisphere and a clockwise rotation in the Southern Hemisphere. It is this process that requires moderate latitude, the Coriolis force is zero at the equator, and is insufficient to organize the storm below about 5 degrees.
  • So, we now have a great deal of wind rushing in towards a center and rotating counterclockwise. If there is a great deal of wind shear (difference in wind speed vs. altitude) the storm can be broken up before it really gets going. However, if the rising column of air in the center can operate, then the storm really gets going. Up at high altitude cool air is pumped outwards away from the center of the storm, this allows more hot, moist air to be sucked in towards the center at sea level, The moisture in this air is condensed heating the air further and driving the whole process faster. Eventually, the center becomes the familiar “eye” of the hurricane.
  • The hurricane can continue for many days over so long as it remains over open, warm water. Over land, the lack of moisture and the increased friction will destroy it rapidly.

Hurricane Forecast Computer Models

  • The behavior of the atmosphere is governed by physical laws which can be expressed as mathematical equations.
  • These equations represent how atmospheric quantities such as temperature, wind speed and direction, humidity, etc., will change from their initial current values (at the present time).
  • If we can solve these equations, we will have a forecast. We can do this by sub-dividing the atmosphere into a 3-D grid of points and solving these equations at each point. These models have three main sources of error:
    • Initialization: When the model starts, if it has an incorrect picture of the initial state of the atmosphere, it will generate a forecast that is imperfect.
    • Resolution: Models are run on 3-D grids that cover the entire globe. Each grid point represents of piece of atmosphere perhaps 40 km on a side. Thus, processes smaller than that (such as thunderstorms) are not handled well
    • Basic understanding: Our basic understanding of the physics governing the atmosphere is imperfect, so the equations we’re using aren’t quite right.
  • The best hurricane forecasting models we have are “global” models that solve the mathematical equations governing the behavior of the atmosphere at every point on the globe. Models that solve these equations are called “dynamical” models. The four best hurricane forecast models—ECMWF, GFDL, GFS, and UKMET—are all global dynamical models. These models take several hours to run on the world’s most advanced supercomputers.
    • ECMWF: The European Center for Medium-Range Weather Forecasting (ECMWF) model is the premier global model in the world for medium range weather forecasting in the mid-latitudes. In 2006, the ECMWF made improvements that starting producing very accurate hurricanes forecasts.
    • GFS: The Global Forecast System model run by the NWS. Excellent graphics are available on the web from the National Center for Environmental Prediction.
    • GFDL: The NWS/Geophysical Fluid Dynamics Laboratory model. The GFDL model that provides specific intensity forecasts of hurricanes. Detailed GFDL graphics are available at NOAA/NCEP.
    • UKMET: The United Kingdom Met Office model. Data from this model is restricted from being redistributed according to international agreement, and graphics from the UKMET are difficult to find on the web..
  • The best forecasts are made by combining the forecasts from three or more models into a “consensus” forecast. Over the past decade, NHC has greatly improved their forecasts by relying on consensus forecast models made using various combinations of the models. NHC forecast has been hard to beat over the past few years.
  • The single best-performing model over the past two years has been the ECMWF. This model out-performed the official NHC forecast in 2010 for 3-day and 4-day forecasts, and in 2009 for 4-day and 5-day forecasts.

European Model is Better at Predicting Hurricanes

  • American and European models have been at odds. In 2012, the American GFS predicted Hurricane Sandy would fizzle over the ocean. The European model anticipated a more disturbing scenario: the storm would turn west and strike the East Coast. Sadly, the Europeans were right. Sandy struck the Eastern Seaboard, causing at least 233 deaths and $75 billion in damage.
  • Overall, the consensus among meteorologists and other scientists is that the European model is better overall in forecasting weather.
  • The main differences between the two approaches lie in data simulation, computing power and the underlying physics used by each.
  • To run these weather track models, scientists start by gathering information about the atmosphere from various sources, including ships, balloons and satellites. Then, using simulations, the data points are packed onto a grid, essentially creating a three-dimensional description of the atmosphere.
  • The Europeans are better at this because their simulation system is better, and they use more data than we do in the US.
  • The European system also draws on more computing power, which enables the model to run on a finer grid, allowing higher resolution and better forecasts.
  • Another important component is the underlying physics used to determine the differing physical properties of clouds. Here again, the European centers do a better job.
  • In addition to running the models at the highest resolution possible to obtain the most accurate forecasts, scientists also conduct something called ensemble models, which allow them to determine the accuracy and consistency of their prediction.
  • To do this, they run simulations at slightly lower resolutions under different hypothetical conditions to determine where the uncertainties are in the forecasts.
  • The European system runs 50 of these cycles, whereas the American GFS only runs 20.
  • The superiority of ECMWF is largely due to Europe’s willingness to invest in software and spend on computers. So they get better results.

Illusion of control: Placebo Buttons

  • Have you ever pressed the pedestrian button at a crosswalk and wondered if it really worked? Or pressed the “close door” button in an elevator, while suspecting that it may, in fact, have no effect whatsoever?
  • The world is full of buttons that don’t actually do anything.
  • They are sometimes called “placebo buttons” — buttons that are mechanically sound and can be pushed, but provide no functionality. Like placebo pills, however, these buttons may still serve a purpose. They provide the illusion of control.
  • In New York City, only about 100 of the 1,000 crosswalk buttons actually function.
  • Worsening traffic may be behind the shift. Crosswalk signals were generally installed before congestion had reached today’s levels, and, over time, they started to interfere with the complex coordination of traffic lights. So they just disabled them.
  • Other cities, such as Boston, Dallas and Seattle, have gone through a similar process, leaving them with their own placebo pedestrian buttons. In London, which has 6,000 traffic signals, pressing the pedestrian button results in a reassuring “Wait” light.
  • So what about the “close door” in elevators? If you live in the US, it almost certainly does not work. The Americans with Disabilities Act of 1990 requires that an elevator’s doors remain open long enough for anyone with disability or mobility issues, to get on board the cab safely. Outside the US, there’s a higher chance, that the button will work.
  • Thermostats in hotel rooms are known to limit the temperature range available to users, thus reducing energy costs. Sometimes thermostats can be deceptive by design. Some models even include a “placebo function” option. Dummy thermostats, those not wired into the system at all, can also be found in offices.