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Grappling With Change: London and the River Thames

• Aug 03, 2010 from scruffydan
  In 1666 Samuel Pepys watched from a little ale-house on the Bankside as much of London burned to the ground. Pepys was no stranger to nature and mankind colluding to produce drama, indeed his diary seems peppered with calamities. The year before London went up in smoke Pepys chronicled the Great Plague of 1665. On 20 May of 1663 the prolific diarist noted a combination of rain, wind and tide leaving important portions of the city navigable only by boat: Then to Westminster, where by reason of rain and an easterly wind, the water was so high that there was boats rowed in King Street and all our yard was drowned, that one could not go to my house, so as no man has seen the like almost, most houses full of water. Without the River Thames there would be no London but like many great cities living with a river the relationship of the two can as tempestuous as it is intimate. This is London so unsurprisingly the little ale-house from which Pepys viewed London's incineration is still in business today, operating as The Anchor. One may purchase a pint of London Pride ale in The Anchor, saunter out to the Embankment and not 75 feet from the door get a direct view and appreciation of London's fruitful but perilous marriage with the River Thames and the estuary and ocean it feeds. Depending on time, tide and winds, looking over the embankment directly in front of The Anchor water is visible directly below at a vertical distance ranging from perhaps 2 to 10 meters. Across the river, the seat of the United Kingdom government and a substantial fraction of the world's economic brain is situated in similar proximity to copious amounts of water, benign or destructive depending on whether the flow remains inside or outside of the Embankment. The Embankment creeping into this narrative needs explanation. Pepys' ale-house viewpoint is located in a neighborhood of London's Southwark Borough known as Bankside; the Embankment is an engineered physical feature of London with roots extending back to Roman times and is a crucial part of London's infrastructure. When this region first attracted settlement, leading to the nurturing of a city of some 7.5 millions, nobody knew of the long term behavior of the conveniently located plain next to the river. London as it turns out is largely situated in a floodplain steadily sinking in relation to sea level yet substantial human investment preceded familiarity with the local environment. The result has been a never-ending battle to keep the River Thames contained within its channel, a ceaseless tightening of the grip of water on London and London's constraints on that water itself even as London thrived on the benefits such a river can bring. Thames Embankment Improvements, 1879 (1) to 1953 (4) (After Defra/Environment Agency Joint R&D FCERM Programme R&D Technical Report FD2319/TR ) Conurbations such as Greater London expose and grow risks even as they sprout and nurture population and architecture. Ideally newly emerging risks will be tackled by public cooperation to the extent they are intellectually, physically and economically tractable. Thanks to efficiently applied public policy in the form of better construction and city planning standards, London's risk of burning from unchecked fire is reduced, just as public policy informed by science has essentially eliminated the chance of contracting plague, or cholera from a drink of London tap water. Government acting in the public interest has also addressed the risk of flooding on the scale witnessed by Pepys yet the optimal solution to this threat is in a continual state of evolution as our understanding of influences on the behavior of the Thames improves. The flood control and emergency response schemes created during the latter part of the 20th century and now protecting London couldn't account for impacts on sea level and storm intensity from climate change, an oversight borne of circumstantial ignorance, now being dealt with in planning revisions and upgrades to London flood management policy and technical solutions. There is a possibly apocryphal story of King Cnut (aka Canute) setting up his throne on a beach of what was in the 11th century Thorney Island and commanding the river tide to stop, which order it failed to obey. Cnut is said to have done this as an example to his courtiers of the limits of temporal power. Real or not, Cnut's demonstration resonates thanks to its simple lesson of the limits of human power against natural forces. Today Cnut's Thorney Island is no longer an island and is the location of London's Westminster Palace, the location of the House of Commons and House of Lords and the functional seat of the United Kingdom government. Despite sinking land and a rising river, Westminster remains high and dry; engineers, money and sheer stubborn human nature have accomplished what Cnut's command could not. Our...

Hardware For Custom Gaming Computers Guide By Centaurus Computers

• Sep 12, 2010 from yetiworks(Yeti Works) in *
  Author: Alex Raven
  
  If you want to purchase a new custom gaming computer you will have a lot of options to choose from, almost every custom PC website offers multiple upgrades but little or no explanation. In this first part of the Custom Gaming PC buying guide you will learn about motherboards, processors, CPU cooling and memory. Next part will give an insight on videocards, cases, cooling, power supplies and more.
  When you pick computer with a cheaper processor it will most likely come with low budget motherboard, expensive processors are paired with advanced motherboards. It is done for the whole purpose of the balance between CPU and MB - you don't need SLI or CrossFire with cheap AMD CPU so why spending your money on it? All motherboards differ by the CPU socket type they support, memory configuration and extra features like number of USB ports, integrated GPU (video), SLI or CrossFire support.
  AMD Motherboards:
  AMD 740G- basic board usually MicroATX with standard limited number of features - Phenom II support, 4-8 USB ports, single PCI-e, 100Mbps Ethernet, 2-4 memory slots (4-8Gb RAM), basic sound system with 5ch support. Good for basic computer, onboard video (ATI Radeon 2100) is low level and usually deactivated for discrete videocard.
  AMD 760G - practically same as 740G but with better CPU support, Gigabyte Ethernet, 6-8 USB ports, Integrated video - ATI HD 3000, may have HDMI port, 8ch sound system.
  AMD 770- most popular board due to the low price and any features possible included. No onboard video but CrossFIre support available, all AMD CPU supported, 4 memory slots - up to 16Gb RAM, 8-12 USB ports along with FireWire. HD sound with Optical and/or Coax SPDIF. Full size board with DDR3 support.
  AMD 785G - latest in integrated GPU boards, ATI Radeon 4200 chipset onboard, all possible features included - eSATA, up to 16Gb RAM, CrossFire available, 6-8 USB ports, DDR3 support, HD sound SPDIF and HDMI output.
  AMD 790X - almost same as AMD 770 but with DDR3 and CrossFire as standard features, plus USB 3.0 and SATA-III available. Most advanced motherboard with most features and best speed in gaming and heavy load applications.
  Intel Motherboards:
  Intel G41- very basic board usually MicroATX with limited number of features - Core 2 Duo/Quad support, 4-8 USB ports, single PCI-e, 100Mbps Ethernet, 2 memory slots (4-8Gb RAM), basic sound system with 5ch support. Good for basic computer, integrated Intel video GPU is useless and usually deactivated for discrete videocard.
  Intel P43/45 - very good designed board with many modern features, up to 16Gb RAM with DDR3 possible, single PCI-e, full LGA775 CPU support, 6-10 USB, Gigabyte Ethernet, fast northbridge and effective overclocking.
  Intel H55- great board for LGA1156 processors with lots of features available. Onboard video through Intel Core i3/i5 CPU with HDCP support, Intel i3/i5 CPUs supported, 4 memory slots - up to 16Gb RAM, 8-12 USB ports along with FireWire. HD sound with Optical and/or Coax SPDIF, DDR3 and HDMI onboard.
  Intel P55 - it is an analog of H55 without video ports but full i5/i7 LGA1156 support, CrossFIre available, fullsize board, DDR3, eSATA, optical SPDIF.
  Intel X58 - most advanced Intel board with all possible features as well as SLI and CrossFire support, 3 channel DDR3 memory, lots of SATA and USB ports, LGA1366 Intel i7 CPU support with future additions to LGA1366 line projected - very good investment in the future of technology.
  Intel Core i7processors deliver an incredible breakthrough in PC performance. They are the best desktop processors on the planet. You'll multitask applications faster and unleash incredible digital media creation. And you'll experience maximum performance for everything you do, thanks to the combination of Intel Turbo Boost technology and Intel Hyper-Threading technology (Intel HT technology), which maximizes performance to match your workload. Works with X58 boards with all features possible SLI/CrossFire and triple channel RAM.
  Core i5 Quad Core can match i7 performance with similar clock speeds and basically same feature set, but will be a cheaper option because they employ P55 motherboards instead of expensive P55. You loose 3 channel RAM for regular dual channel, limited CrossFire (16x + 4x PCI-e vs X58 dual 16x speed), and almost non existent SLI support. Otherwise same features so in most cases it will be on par with i7/X58 combo, but will loose in heavy multithreaded applications with lots of RAM usage and in heavy gaming with multiple videocards used. Still a very good option considering a few hundred dollars saved and less heat from the CPU which is great for overclocks.
  Core i3 and i5 Dual Core with Video Core integrated - require H55 motherboards which are not expensive and have nice features and options but mostly no CrossFire or SLI support and only dual channel RAM. Processor itself is much faster than previous generation dual cores but looses greatly to most quad cores in multithreaded...

The Best, Cheapest Ways to Upgrade Your PC [Parts]

• Jun 30, 2010 from gizmodo(Gizmodo) in Technology
  Upgrading your PC can be a head-spinning process. Our Lab experts help you sort through the chaos with 18 products that won't break the bank.
  The art of the PC upgrade is simultaneously an expression and a test of one's diagnostic skills, computing savvy, and fiscal sensibilities. Identify the bottleneck. Research the parts that will fix the bottleneck. Remove the bottleneck.
  As always, price and performance are the pivot points. After all, you can't just toss $1,000 at your system to level it up. Well, you can, but in most cases you'd be a fool for doing so.
  When the Maximum PC staff convened in conference room Spock to plan this story, we decided to establish some ground rules. First, we challenged ourselves to stick to our theme of a successful budget upgrade. This meant avoiding the tendency to fall back on the most expensive, best-of-breed components in each category.
  Instead we forced ourselves to take a more nuanced approach. In each category, we expended considerable energy determining which product(s) owned the sweet spot-top-left on the 2x2 grid if you're graph-happy-of the price-performance ratio. Staying consistent with our real-world theme, we used real-world pricing from sites like NewEgg and Amazon. Because we're talking about upgrading an existing machine, you'll find no case or mobo recommendations here.
  Without further adieu, we happily present the results of our research. Below you'll find a bevy of product recommendations that prove you don't have to break the bank to achieve substantial gains in performance.
  Solid State Drive
  40GB Intel X-25V
  It's easy to argue that a budget SSD doesn't actually exist. That said, a $125 solid state drive can qualify as a budget upgrade in some contexts-and only some of those contexts involve recreational drugs.
  Intel's X-25V solid state drive (the V stands for Value) doesn't have the fastest sustained write speeds (think 50MB/s, not 200MB/s), but its sustained read speeds top 150MB/s and its random-access writes are triple any of its peers'. This makes it perfect as an OS drive, which relies more on reads and writes than on sustained writes.
  
  If you don't mind keeping data on an external drive or SD card, a 40GB Intel X-25V can also offer a substantial speed boost to the 5,400rpm drive on your netbook or older laptop. And if you're moving to Windows 7, the X-25V supports TRIM, which will prevent performance degradation. $125 is a lot for a hard drive, but for an SSD, it's downright reasonable given the performance bump you'll experience.
  SSD for $125
  TRIM support prevents degradation
  Mechanical Drive
  Seagate Barracuda 7200.12
  In the old days, the prospective hard drive buyer had to choose between high performance and high capacity. Heck, if you're planning on upgrading, you probably don't have either.
  Fortunately, while solid state drives have thoroughly usurped the highest end of the performance spectrum, mechanical drives still rule the capacity roost, and they're only getting faster. To wit: the 1TB Seagate Barracuda 7200.12, which costs just $80 and offers sustained read and write speeds of over 100MB/s.
  
  While it can't match the speeds or random-access times of WD's VelociRaptor drives or SSDs, the 1TB Barracuda is capacious enough for all your apps and data-unless you're in the habit of ripping Blu-ray discs, of course. So, if your OS drive is getting long in the tooth (or just running out of room), moving to a 1TB Barracuda 7200.12 will buy you some breathing room and a substantial speed boost.
  1TB for $80 defines Budget Upgrade
  Perfect single-drive solution
  Optical Drive
  Samsung SH-B083L
  If you're currently performing DVD chores with a 16x burner, an upgrade to a higher burn-speed rating is beyond cheap (shoot, our current Best of the Best 22x Samsung SH-S223 is $20), but not all that satisfying in terms of performance gains. With DVD media stuck at 16x, higher-rated drives only exceed that limit when burning to discs of a particular brand. And even then, you're looking at a time savings of maybe a minute. Big whoop.
  
  Instead, consider the benefits of upgrading to a BD-ROM combo drive. You can get Samsung's SH-B083L for $100. It gives you the ability to enjoy HD Blu-ray movies on your newly upgraded display, while still offering respectable 16x DVD+/-R write speeds. In our tests, the SH-B083L's performance was on par with the more expensive Plextor PX-B320SA in everything but DVD ripping, where the Samsung took 15:17 to copy a dual-layer disc vs. 10:47.
  Affordable, speedy blu-ray performance
  Videocard
  ATI Radeon HD 5850
  When it comes to videocards, you can count on today's $300 product being superior to the top-shelf product from two generations back. That's certainly the case with cards based on the ATI Radeon HD 5850 GPU, which not only deliver superb performance, but do so without requiring a massive power supply.
  What might it be replacing? If your gaming rig is three years old and you invested in a high-end videocard, it would have...

Radio propagation

• Sep 28, 2010 from weatherforecas
  Radio propagation
  Free space propagation
  In free space, all electromagnetic waves (radio, light, X-rays, etc) obey the inverse-square law which states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from the source or:
  Doubling the distance from a transmitter means that the power density of the radiated wave at that new location is reduced to one-quarter of its previous value.
  The power density per surface unit is proportional to the product of the electric and magnetic field strengths. Thus, doubling the propagation path distance from the transmitter reduces each of their received field strengths over a free-space path by one-half.
  Modes
  Radio frequencies and their primary mode of propagation
  Band
  Frequency
  Wavelength
  Propagation via
  VLF
  Very Low Frequency
  330 kHz
  10010km
  Guided between the earth and the ionosphere.
  LF
  Low Frequency
  30300 kHz
  101km
  Guided between the earth and the D layer of the ionosphere.
  Surface waves.
  MF
  Medium Frequency
  3003000 kHz
  1000100m
  Surface waves.
  E, F layer ionospheric refraction at night, when D layer absorption weakens.
  HF
  High Frequency (Short Wave)
  330 MHz
  10010 m
  E layer ionospheric refraction.
  F1, F2 layer ionospheric refraction.
  VHF
  Very High Frequency
  30300 MHz
  101 m
  Infrequent E ionospheric refraction. Extremely rare F1,F2 layer ionospheric refraction during high sunspot activity up to 80MHz. Generally direct wave. Sometimes tropospheric ducting.
  UHF
  Ultra High Frequency
  3003000 MHz
  10010cm
  Direct wave. Sometimes tropospheric ducting.
  SHF
  Super High Frequency
  330 GHz
  101cm
  Direct wave.
  EHF
  Extremely High Frequency
  30300 GHz
  101mm
  Direct wave limited by absorption.
  Surface modes
  Main article: Surface wave
  Lower frequencies (between 30 and 3,000kHz) have the property of following the curvature of the earth via groundwave propagation in the majority of occurrences.
  In this mode the radio wave propagates by interacting with the semi-conductive surface of the earth. The wave clings to the surface and thus follows the curvature of the earth. Vertical polarization is used to alleviate short circuiting the electric field through the conductivity of the ground. Since the ground is not a perfect electrical conductor, ground waves are attenuated rapidly as they follow the earth surface. Attenuation is proportional to the frequency making this mode mainly useful for LF and VLF frequencies.
  Today LF and VLF are mostly used for time signals, and for military communications, especially with ships and submarines. Early commercial and professional radio services relied exclusively on long wave, low frequencies and ground-wave propagation. To prevent interference with these services, amateur and experimental transmitters were restricted to the higher (HF) frequencies, felt to be useless since their ground-wave range was limited. Upon discovery of the other propagation modes possible at medium wave and short wave frequencies, the advantages of HF for commercial and military purposes became apparent. Amateur experimentation was then confined only to authorized frequency segments in the range.
  Direct modes (line-of-sight)
  Line-of-sight is the direct propagation of radio waves between antennas that are visible to each other. This is probably the most common of the radio propagation modes at VHF and higher frequencies. Because radio signals can travel through many non-metallic objects, radio can be picked up through walls. This is still line-of-sight propagation. Examples would include propagation between a satellite and a ground antenna or reception of television signals from a local TV transmitter.
  Ground plane reflection effects are an important factor in VHF line of sight propagation. The interference between the direct beam line-of-sight and the ground reflected beam often leads to an effective inverse-fourth-power law for ground-plane limited radiation. [Need reference to inverse-fourth-power law + ground plane. Drawings may clarify]
  Ionospheric modes (skywave)
  Main article: Skywave
  Skywave propagation, also referred to as skip, is any of the modes that rely on refraction of radio waves in the ionosphere, which is made up of one or more ionized layers in the upper atmosphere. F2-layer is the most important ionospheric layer for HF propagation, though F1, E, and D-layers also play some role. These layers are directly affected by the sun on a daily cycle, the seasons and the 11-year sunspot cycle determines the utility of these modes. During solar maxima, the whole HF range up to 30MHz can be used and F2 propagation up to 50MHz are observed frequently depending upon daily solar flux values. During solar minima, propagation of higher frequencies is generally worse.
  Forecasting of skywave modes is of considerable interest to amateur radio operators and commercial marine and aircraft communications, and also to shortwave broadcasters.
  Meteor scattering
  Meteor scattering relies on reflecting radio waves off...