How was security on the Silk Road between China and the West maintained?

Question: From the 2nd century BC to the beginning of the 15th century the Silk Road (or more correctly roads, as there were alternative routes) was the primary trade route between China and the West.  One would think that a trade route would invite highwaymen and substantially raise the cost of shipping valuables. How then was security of the merchants traveling on the Silk Road assured?  Did they have to ride in large caravans, convoy-style?  Pay "protection" fees to tribes along the way?  Or did the major powers along these roads provide a police presence?  Were there checkpoints or fortresses along the road?  The latter seems possible to me because with the fragmentation of the Mongols and the rise of the Ottomans in Asia Minor the silk road came into disuse and a motivation factor for the Portuguese and others (e.g. Columbus) to look for a sea route to China in the late 15th and early 16th centuries.
Comment: @MarkC.Wallace When I ask questions, I'm trying to get good answers.  All that is needed is enough information to get someone's juices running and to keep the scope of the answer somewhat limited.  You'll find at other Stackhouse sites, the best questions are often asked by neophytes who know little but want to learn.  I don't like when sites play "stump the expert" or questions are asked to show off the OP's brainpower.
Comment: @BruceJames Eloquently stated. I had to reconsider my position after reading this. I won't carry out the discussion here, but I wanted to recognize a well articulate counterargument.
Comment: What research have you done? Have you researched the etymology of the word *caravan*? Have you at a minimum read the Wikipedia article on the Silk Road?
Comment: @PieterGeekans Yes, I read the Wikipedia article on the Silk Road.  It does not really answer this question; it suggests that the big states had an interest in keeping it running, but they do not explain how, or to what extent, peace on the road was maintained.
Comment: I think this question _should_ show more preliminary research, but I'm reluctant to close a question with an excellent answer.
Answer: Mentions of Bandits and robbers:
Bandits and robbers were a constant threat on the Silk Road. Xuanzang mentions several encounters with bandits.

Near Dunhuang, the Silk Road split in two to skirt the rim of the
  Taklamakan Desert. The roads met again 1400 miles west at Kashgar. But
  between these two oases lay the Silk Road's most dangerous terrain.
  Among the threats were starvation, thirst, bandits, and ferocious
  sandstorms that were known to bury entire caravans.

The Mogao Caves near Dunhuang are laden with Buddhist art spanning a period of 1000 years. Most of the images are religious, but there are also images of everyday life. There are scenes that show travelers on the Silk Road, and some portray bandits.
The Logistics:
The Silk Road goes through some of the most challenging terrain in terms of vast deserts and high and rugged mountain ranges. The terrain, the weather and many other risks did indeed result in higher transit costs. Bandits and robbers certainly added to the risk. But several systems were in place to reduce the risk.
Few people ever traveled the full length of the Silk Road. The goods were transported by a series of routes and agents. This mode meant that local agents, familiar with terrain, politics, and bandits of their own region, who were better suited for the task, would ensure safe transit.

The shipment of goods from South Asia to Central Asia (or vice versa)
  was a long process that involved a number of transporters, which
  resulted in high transit costs. Whether the transporters were local
  villagers in the role of kiraiyakash or professional long distance
  porters such as the caravan men in Rasool Galwan's autobiography
  (Galwan 1923), the transporters of goods through Ladakh had to be well
  informed concerning regional conditions, and familiar with the
  terrain. Landslides, sudden snowstorms, and bandits were just a few of
  the hazards faced by those transporting goods through Ladakh.
Source: Trade and Contemporary Society along the Silk Road

Travelers joined caravans to benefit from safety in numbers and experience of the caravaneers gathered from their previous trips.

Caravans were used mainly in desert areas and throughout the Silk
  Road, where traveling in groups aided in defense against bandits as
  well as helping to improve economies of scale in trade. --
  Wikipedia

Another important choice was in the the routes used by the merchants, which were selected according to the political stability of the regional power. Centralized states, confederations and regional powers promoted trade and diplomacy. They invested in communications and economic infrastructure such as secure roads, water depots, inns, reliable coinage, standard weights and measures. They imposed taxes on travelers and traders. The merchants found it wiser and safer to pay the controlling authorities for safe passage than to risk encounters with bandits.

Defense against banditry took place at private and institutional
  level. Caravans of goods needed their own guards against plundering by
  the bandits (i.e., for security risk), and this was an added cost for
  the merchants making the trip. The institutional level had three
  forms: The Chinese garrisons and watchtowers beyond the Great Wall,
  Mongolian postal stations, and caravanserais in the Middle East and
  Anatolia. These institutions provided safety, supplies, and lodgings
  for merchants. Besides, the Chinese soldiers informed about incidents
  using smoke and flag signals in real time.
Source: Managing Supply Chains on the Silk Road

Different groups rose and fell through the ages, gaining political and military power, and hence controlling the trade along the Silk Road. Trade along the Silk Road was at its zenith during the Tang dynasty due to the stability of the government.
The travelers along the Silk Road changed over time. Chinese, Yuezhi, Bactrians, Indians, and Sogdians were the first to create the historical Silk Road in Central Asia in the first century BC. In time Muslim powers came to control large parts of the road.

Islamic patrons built hostels, known as caravanserai, that
  accommodated both people and beasts of burden. In addition, the Seljuk
  Turks who controlled the western part of the Silk Road offered the
  traders a special guarantee of safety. The government assured their
  financial security by paying compensation out of the state treasury
  for any loss caused by robbery. The Turkish authorities, whether the
  unified Seljuk sultanate or independent amirs, also built fortified
  caravanserais that provided food, fodder, and lodging for the
  travelers at intervals of one day's journey apart all along the trade
  routes.
Source: The Silk Road in World History

Taking into account the the time taken for 1 day's travel, caravanserais were strategically located on the trade routes at distances of 25 to 40km from each other. The topography, of course, affected the distance of the caravanserais. The caravanserais not only sheltered caravans, but also served as military stations.
And lastly, there was also Insurance.

The Seljuk Sultanate of Anatolia created a state insurance policy in
  order to manage the security risks of land and sea traders whose goods
  are damaged or stolen due to bandit, pirate, and neighboring state
  attacks (Turan, 2009). For insurance purposes, contracts were signed
  between caravaneers and merchants that guaranteed the quantity of the
  goods and also reduction in the transportation fee if any delays
  occurred. Similar transportation contracts are used by third part
  logistics firms in today's supply chains.* The caravaneers kept lists
  of goods carried with specifications such as variety, weight, and
  volume (Matthee, 1999). This practice is the origin of today's bill of
  lading in global supply chains.
Source: Managing Supply Chains on the Silk Road
Comment: Thank you very much for the links to books, especially the supply chains one.
Answer: The Silk Road was very secure during the peak of the Mongolian Empire, basically the early 13th to 15th centuries.
Most of it was subsumed in Mongol controlled territory, and the movements of troops along or around it also acted as a "policing" mechanism.
Prior to the Mongols, the nearly-as-ferocious Turks maintained the security over most the Silk Road.
During times when there was no "dominant power," bandits and robbers were a real problem, as pointed out in other answers. At such times, only relatively short "stretches" of the roads, between nearby cities, were reasonably safe, and most of the shipping took place over those stretches in "relays." People that went beyond those relatively safe stretches really "paid their money and took their chances."
Comment: Not your best answer, Tom.


I'm creating an original setting for D&D—where do I start?

Question: Creating a new fantasy setting for D&D is daunting but I don't want to use one of the published settings. I have a blank piece of paper in front of me and a whole world to create. My friends want to play as soon as possible. Where's the best place to start?
Comment: Related: http://area51.stackexchange.com/proposals/63276/worldbuilding
Answer: I would do the following. Note this is also found on my blog here .
Using one page sketch a world or continent mapLabel important regionsWrite one page of background giving no more than a handful of sentences to each region.Pick an area roughly 200 miles by 150 milesGrab a 8.5 by 11 sheet of hex paper. The scale should be so that it represents a 200 by 150 mile regionDraw in mountainsDraw in riversDraw in hills using them to divide the region into distinct river valleyDraw in vegetation (swamps, forests, desert, etc)Decide to place Population Locales note their race this includes social monstersDecide to place Lairs (locales tht revolves around a home of monsters)Decide to place Ruins (locales that revolves around a site)Decide to place miscellaneous locales. (anything that doesn't fit a above.Name your geography (don't forget islands)Write a Half Page background describing the region and it's history.Write a paragraph describing each named geographyWrite a paragraph describing each Population LocaleWrite a paragraph describing each Lair (you could get away with a stat block)Write a paragraph describing each RuinLook at your notes and come up with two to four plots that ties one or more locales together. Write a paragraph or two on each.For each population locale come up with three to five encounters. They should be a sentence each.Come up with 6 to 12 general encounter for the region as a whole. Should usable in any area of the region. They are a sentence or two each.Pick the 4 or 6 most important Population locales and draw a quarter page sketch map of the settlement. Pick the starting population locale and draw a full page map of the settlement. This is the "Home Base" Use Medieval Demographics to get an a idea of how many shops are in the town. Pick or create 6 or 12 important buildings. Write a paragraph each. Scan your descriptions for NPCs or noted monsters. Write a two sentence about each. The first a one line with minimal stats the second one sentence. This is your roster. Pick the 12 most important NPC or MonstersWrite a paragraph describing each and fully stat them.Pick the most six common encounter type. (City Guard, Border Warders, Bloody Hand, Orcs) Write a paragraph and fully stat them.Scan your description for any regional organization and write a paragraph on them. Fully stat the most common encounters involved with them.Make up a rumor chart with 10 to 20 items that feeds the players into the encounter and plots you created in above.Identify major regions and create a random encounter chart for each (monsters, wildlife and NPCs) [Thanks Jeff I just plumb forgot]

This will probably run to about 10,000 words. You can do this in about 2 weeks spending about 2 hours an evening at a 1,000 words a evening and time drawing maps. Or consider it about 24 hours of work.
This is being expanded in the following posts.
A Fantasy Sandbox in detail Part I covers Step 1
A Fantasy Sandbox in detail Part II covers Step 2,3, & 4
A Fantasy Sandbox in detail Part III covers Step 5,6,7,8,9, & 10
A Fantasy Sandbox in detail Part IV covers Step 11, 12, & 13.
A Fantasy Sandbox in detail Part V covers Step 14,  & 15.
A Fantasy Sandbox in detail Part VI covers Step 16.
A Fantasy Sandbox in detail Part VII covers Step 17.
A Fantasy Sandbox in detail Part VIII covers Step 18, 19, & 20.
A Fantasy Sandbox in detail Part IX covers Step 21
A Fantasy Sandbox in detail Part X covers Step 22
A Fantasy Sandbox in detail Part XI covers Step 23
A Fantasy Sandbox in detail Part XII covers part of Step 24
A  Fantasy Sandbox in detail Part XIII covers part of Step 24
A Fantasy Sandbox in detail Part XIV covers part of Step 24
A Fantasy Sandbox in detail Part XV covers part of Step 24
A Fantasy Sandbox in detail Part XVI covers part of Step 24A Fantasy Sandbox in detail Part XVII covers Step 25
A Fantasy Sandbox in detail Part XVIII covers Step 26
A PDF Collecting the above steps into a printable book can be downloaded.
Answer: You've got a blank sheet of paper, and you want to play ASAP. Excellent. This is what I've done successfully:

Decide with your players what kind of setting it should be. You can skip this if you're playing in the assumed setting of your game. Otherwise, find out what elements your players want to explore. Should there be firearms? Political machinations? Should it focus on slice-of-life play, or an epic destiny to save the world? This step should probably be done prior to sitting down at a table with that blank sheet of paper—depending on what is decided, you may have some system hacking to do before moving to the next step.
Have your players make their characters. Make sure they chat about their characters as they do. If they ask something like, "Is there a place where lots of X live?" the answer is "yes" and encourage them to ask more such questions. They just helped you create a bit of setting.
Draw a map. This doesn't have to be pretty, just useful. Make sure there are features relevant to the characters that are currently developing. Lots of thieves? Have a big sprawling city somewhere. Rangers and druids? Don't skimp on forest and places where settlements clash and/or co-exist with nature. This is you making a "character" that fits in with the players' characters.
Flip over your sheet of paper and start making lists. For each interesting place on your map, make a list of things, people, monsters, and events that could be met/stumbled upon/spotted/hunting the PCs. Number these lists for easy random-encounter rolling, or use them as handy pick-lists for when you need inspiration.

You're ready to play!
After your first session, follow up with:

Think about the characters more. What makes them tick? Build some plot hooks and keep them handy to inspire you during play.
Make your map pretty and add details. Your first map needed to be useful, but this one should be a bit more inspiring to you and your players. Now that you've got a bit of time, make your map make you want to play there more.
Refine and extend your lists. Rejigger the probabilities of your random encounter tables, add more interesting items, cross off things that you've used that aren't going to happen again, and add more tables to flesh out the world more. Not only are these tables directly useful when playing, but they're a quick and easy way to make the world come alive and inspire thoughts. Why are there a clan of gnomes living in the same hills as a ferocious ogre? How do they or don't they get along? Daydream a bit, and see what comes out.
Comment: Perfect. I know there's a +17 answer (at the time of accepting this one) and it's incredibly useful. However, I think that laundry list might overwhelm someone new to world-building. This answer captures a very simple procedure for starting quickly and building upon that beginning. They can always "graduate" to the other answers.

Thank you, everyone!
Answer: Start with what you know you and your friends like.
You should establish a basic setting and campaign focus, depending on the themes you know your players will enjoy. Decide if its going to focus on combat, investigation, exploration, etc, and if the setting fits or inverts that style of play. For example, a campaign that takes place in Rome during the height of the Western Empire lends itself well to investigation, but less so to exploration.
As an example, I had a group of players that liked role playing and investigation. I started a campaign set in an alternative 950 AD Bavaria, where enemies could be fierce but were more likely to run away if they dropped below 50% hitpoints - meaning, they were always willing to talk first and cut a deal.
Add a base and adventure location.
Knowing the above, you should have base culture/setting in mind. Add a starting base and and adventure location, plus 3-4 additional encounters and 2-4 NPC personalities. Again, focus on what your players like and don't like. Don't run an adventure after Sunday school that features a base at a brothel.
In the adventure above, I started with an inn located on a recently flooded river and a hidden fortress under a waterfall, complicated by a small tribe of starving goblins and a creepy harpy that never revealed herself.
Take notes during the first session.
Most adventures I run "create" future adventures through how players treat the NPCs. Attach facts to NPCs as they are played, and listen to what your players think about them. If NPCs develop personalities during the session, you should fill out their backgrounds and associated locations before the next session.
During the adventure above, an orc who was staying with the goblins became the focus of a bait and switch with a sword with a continual light spell on it. The players loved the NPC so much, they persuaded a new player to play the orc character. The players also were interested in where the goblins came from, and why the harpy was so afraid to show herself.
Build out from the first session.
After the first session, add more surrounding details. Put that dungeon location and the base into a more defined region, and add a new dungeon location.
After the adventure above, I knew I had to locate the goblin's lair, and fill out the background of a ghost (from which the harpy was hiding) as well as a nearby tiny town where the players would eventually train.
Comment: This is very close to my favorite answer. =D
Answer: What I would not do:
Try to create a campaign setting.
What I would do:
Make a list of all the ideas and concepts I want to use in the setting.
Put the list away and go and make a cup of tea.
Go through the list and make connections between the items.
Leave all the dangly bits, because I'll find ways to connect them later.
That's it. Really. You don't want to try to create the whole thing from scratch or, and this is important, it will never happen. Start small, start with a bunch of ideas, build outward as the game goes on. Ideas will occur in play which would never have done so beforehand, and best of all, the players will come up with ideas that you can pinch and include.
Here's a (truncated) example of one of my lists:
Zombie apocalypse
Colony
Solo/iconic monsters
Adventurers-as-celebrities
Adventurers' Guild
Shadow of the Colossus
So what have we got? Well, let's say the zombie apocalypse rendered the original continent on this world uninhabitable, so there was a diaspora. One of the destinations was a small colony on the shore of a distant land, and now this colony is the main setting for the game. The new continent is vast and unexplored, and with many, if not most, of the fighting types having been killed in the Zombie Wars, probably in some kind of Dunkirk type rearguard action, the taming of this new land is left to the youthful heroes of the new generation (the players).
One particular danger in this new land is that it is ruled by vast beasts. These things stomp about causing all sorts of trouble, and generally make expansion rather difficult for the new arrivals, so a sort of Very Big Game hunting culture has arisen, with groups of heroes going out into the wilderness to take down these titans, and bring back trophies in order to improve their standings in an informal league of adventurers. Though it is serious business, this playful attitude is tolerated, even encouraged, as it inspires more youngsters to sign up to pacify the wilderness.
(In game terms, each of these giant beasts is a huge specimen of an iconic D&D monster, and there's only ever one of them. So there's one huge hydra, one massive manticore, one bloody big beholder, and so on. They're so big they cannot be easily or quickly harmed by simple sword strokes, and the heroes have to come up with more clever methods of attack. There may be an indigenous tribe of orcs or something, but for the most part, there's only one of each monster.)
So there you have a sandbox-type setting, with a base of operations, and a unique feel via the sport analogy and the giant monsters; all that from about fifteen minutes' work.
Answer: Rich Burlew at Giant in the Playground Games has an amazing series of guides to worldbuilding, including a side-along walkthrough of himself creating a setting from scratch.
What it boils down to is two general directions:

Outside-in, where you outline and create civilizations, governments, geography and major history first, and then fill in the specifics and other details as you get to them.
Inside-out, where you create a completely fleshed-out starting point (one city, one concept), and build the world outside from there. An  example would be to have a home city, and put forests and deserts nearby because that's where you want the players to go next. Then you'd create outwards from there as necessary.

The main difference between the two is personal playstyle, in addition to what kind of game you're building it for.
Comment: inside out is usually better if you need to have a detailed world early on.
outside in is usually better if you need the big picture early on.
Answer: I like to start with a village or town and then build and develop a few miles around it.  This gives the players a base of operations, a place to heal and a place to upgrade their gear or blow all their money.  It doesn't take too much time.  Sketch some of the more important locals, a temple a noble or two, a couple guards and some other colorful characters.  Oh of course you are going to need a tavern.
Answer: Step 1: Figure out why
Decide what you intend: Is this a one-shot world? Is it a new setting for a series of several campaigns? For just you? To be shared with friends? To be net-shared? Published?Just your work, or you and others collaboratively?
Step 2: Planning
Start by making several key decisions.
Top-down, or bottom-up. Top down, you start with the world, and detail out chunks smaller and smaller.
Themes: Pick what themes and memes you want to impose.
System(s) pick which game system(s) to do it for. Determine as well how much modification to that(/those) system(s)
Who Writes What? If not doing it all yourself, who is responsible for what parts? make the decisions.
Set a schedule. pick when each chunk is to be done by. Leave extra room.
Step 3: Mechanic Writing and Building
If you need to make modfications to systems, that is the priority. Figure out the changes, and if collaborating, work out how those changes impact the setting. Some people think system doesn't matter, others let system trump setting unless the setting includes rules changes. Examine the impact of any magic, brainstorm those impacts.
Step 4: develop the environment
Bottom-up: If working bottom-up, pick your starting point, and start with the mapping and describing process. For home-use, this is often the preferred mode. Pick the place, and describe the residents, the government, the religions, the physical descriptions, even maps. Make note especially of routes out, which can later be used for dungeons or other locations.
Top-Down: Lay out the map, Picking natural boundaries and resources, and determining cultures and groups by natural boundaries and access to resources. Lay out the physical first, and place cultures upon that. You may want certain physical features for certain cultural issues. Start with a tag for each culture, then add details as you come up with them. (I've run several campaigns on a world where each culture of 30 had a paragraph, and then simply filled in extrapolations and details as my players brainstormed them.)
Both ends inward: Start with the big scale, then pick a spot, and detail it as a bottom-up, but knowing its place in the bigger picture. This is a pretty typical publication mode; several bottom-up locales in a top-down setting; later supplements often do a top-down on a subset, and several bottom up adventure locations.
Step 5: Revise and expand
Pick the parts which interest you, and expand upon them. Don't worry if they're out of scale to what's been done so far. Then, as you fill in, if you find something that feels wrong, revise it.
Step 6: Edit and Playtest and Edit
If you intend to publish it, rather than just play in it, edit it to a playtest document, then find some people willing to try it. Have them play it cold, let them ask a zillion questions. Revise it to answer the questions. Repeat. Then trim back to what is essential.
Step 7: Cut it into publishable chunks
If working for publication, odds are, you're going to either not have near enough, or have way too much. Too much is much to be preferred. Trim down to just a schematic of the largest scale, and pick a workable amount for the first chunk. Send to a new round of (preferably fresh) playtesters. If they can play with that much, and want more, but don't need more to play with, you've the right size chunk. Repeat the process for the other chunks.
In general, if you want to start "right off", for home play, start with a bottom-up, and let the players help design the central elements. You'll be skipping steps 6 & 7, and 5 will be done as you develop more adventures. Having run several campaigns this way, it works really well.
Answer: There is also http://www.io.com/~sjohn/demog.htm also known as
Medieval Demographics Made Easy
You can start either at the top or the bottom, I think its realistic to start at the bottom because starting at the top makes things top heavy I find (its all a nation of orks, a nation of gnolls, a nation of trolls ,etc when realistically the modern nation is not very old.).
Unless I was very averse to it, I would try to get a firm grasp of what feudalism is. Maybe read a bit of history.
You can also start at the very bottom which is game mechanics and build up from there, but that requires a bit more foresight.
Answer: In your context, friends who want to play right now this minute, I'd start with an initial adventure and starting point, seed it with a ton of ideas that the players can follow, and build the world from what they do.
In more concrete terms I'd come up with a basic scenario with at least three "sides", a map of where at least two are (the third side provides the "in"), and at least two personalities per side.  Have side three get the characters involved and then grow from there.  Steal a setup from a favorite movie or book to start.
Worked Example: A Fist of Seven Silver Pieces
South of the last Barony is a colony of people.  The descendants of escaped outlaws they now are mostly simple farmers just trying to eek out an existence.  However, they have found a small cache of old imperial silver they have used to trade for a better life.  Now their mule trains to the last Barony are being raided.  They've hired the adventurers to end the raids.
What the farmers don't realize is there are two groups raiding them, a group of orcs from some local caves and some of the young men of the village using a ruined Imperial border post.
Now, create the two young men leading the raiders and WHY, the orc shamen and chieftan, the village headman and his young daughter (who is in love with the lieutenant of the raiders instead of their leader).
Things that provide hooks for the future: all six characters, the raider's motivation, the ruins, something special about the Imperial silver coins (perhaps minted by a supposedly legendary Emperor-Mage who most don't believe existed but created a grand spell/item...is it in the caves) and so on.  Plus, your players will invent connections you didn't think of...run with them.
Everything here is stolen from common items (two westerns, stereotypes, etc) and is easy to create (cave map, ruined outpost...all easily found online), and six characters.
That could get up you up and running Saturday even.
Answer: I've started a couple of times, years ago, by reading the Dungeoncraft serie by Ray Winninger.
It explains and gives structure to the campaign building process. The second time I used it just as reference but it still was super-useful :)
Answer: I think you need to answer two questions before you follow any of the great counsel offered by other responses: 1) What kind of adventures do I want and like to run, and 2) What kind of adventures does my group like to undertake?
Don't set yourself up for frustration by over-fashioning your own world if, by their nature and temperament, your gamers are more enthused by hack-and-slash and don't require much depth, history, etc. Believe me, you'll find yourself trying to force them to care about the hours of work you put in, and everyone will be dissatisfied.
If every now and then they like to dabble in some history, but not much, buy someone else's world and adapt according to your good pleasure--that's your prerogative.
If your group loves geological and historical and magical histories and background and depth, then by all means, go ahead!
Answer: If you're like me, a lazy DM, then I suggest the following: Start with an initial adventure, an initial town, a handful of NPC names, each with a one-line description of what they look like and how they behave. I like hex maps so I'll pick six adventure ideas and place them around the starting area. I'll write a random encounter table. If you're good at improvising, just use a random monster table (and maybe some wandering NPCs?) that reflects the seven locations you have and the general area. If you need more structure, prepare a real encounter with each of the monsters and NPCs you picked. Then start to play. Keep adding just-in-time information and adventures as the game develops.
This approach makes sure that you don't waste a lot of time on stuff that won't get used. It treats actual gaming as top priority and assumes that you don't enjoy world-building per se. If you do, ignore this advice. :)
Answer:
Talk to the (other) players. Talk to them again while you design.
Start from what you're excited about, and make it central to your game.
Skip whatever you're not excited about (chances are you'd make it boring anyway) and get to the exciting parts.
Start small. Don't design anything more than what you strictly, absolutely need for your first session(s). In Storming the Wizard Tower, Vincent has it right.
Leave some blanks at the edge of the map, so to speak, to allow for later growth. Do have a bunch of half-formed ideas, if you like, but don't plan ahead yet, don't commit.
Look at the rules of the game for inspiration. What is it that, in your mind, feels awkward and in need of a fictional justification? Provide that justification.
Look at the rules of the game for inspiration. What is it that, in your mind, feels too awkward for any amount of justification to redeem it? Throw it away and design around the gaping hole you're left with.
Pause for a moment and look at what you made: what sets this setting apart? Nice. Remember to reinforce that at every chance, except those rare occasions when you'd really love a big change of pace.
What you'd love the most to do, if anything, do it. Otherwise, just do the obvious thing.
Love what you're doing.
Love what you created, but don't wall it away. Let the player characters make a huge impact. If you discover you're walling it away, dig some PC-sized holes through the wall.
If you don't feel like you're loving what you made, let it drop and start anew.
Answer: Gather your players together and run a game of Microscope.
I've only done this for one game so far but it's generated a very interesting world history that the players have had input to and so know some background for immediately. I then expanded on this history and filled out interesting places and events hinted out by the Microscope gave.
Comment: +1! *Microscope* is tonnes of fun all its own, and as a bonus? You never have to worry again about the players not knowing the setting! One pitfall that's not hard to avoid but might need talking about before the game is that everyone has to be on-board with making the game of Microscope obey the fictional constraints of the system you'll eventually use, e.g., if you're playing *D&D* then keeping in mind how magic works in that system helps to avoid creating a setting that will require significant system hacking later.
Comment: @SevenSidedDie A test game beforehand perhaps to get the players into the mindset might help, that and careful use of the palette to constrain the world concepts.
Answer: I have two rules for setting generation: Broad and Small.
Broad
A few sentences that tell you why this setting is going to be AWESOME (by whatever definition you use).  These are broad strokes, designed to help you stay focused on what things to include or flavor to go for.  "Dragons psionically holding together the Material Plane against Cthulhu things.  Airships powered by sentient meteorites.  Repeating design work on everything, interlocking like Islamic art."
Small
A town, a few interesting NPCs.  A dungeon or place of adventure, a few interesting NPCs.  Within this situation, put in a few rumors, hooks and potential directions things can go from there - if the players show interest, you know what section to develop next.
The players will make up backstories too, which also helps develop your world.
Broad covers the fun unique parts, small is the parts the players regularly engage with.  Don't build stuff unless it's very likely to see play - no point in making 200 pages of setting if you only play 5 sessions.
Answer: Building a fantasy setting is hard, damn hard. You have to think a lot of things and make them coherent. Also, you don't have to have dark spots. The best to do is to create a "small island" in a well-built, pre-made setting.
That said, if you really want to develop a setting all by yourself, you should define the following things first:

Type of creatures you want to inhabit your world. Only humans (such as middle ages Europe) or not ?
Level of magic. No magic at all ? Scientific-based magic (such as alchemy) ? Very low power magic ? Or a magic feast like in Forgotten Realms ?
The terrain. Define the world map, together with geographic features, such as mountains and rivers. If you want to be picky, try to follow proper rules for orography. An example of notable offender is LoTR: under no circumstance Mordor can arise from proper geology.
Define the countries/kingdoms, normally following geographic features (rivers/mountain chains), give them cities, villages, resources (mines/crop fields), temples, religions, preferred races, language and coins, a king/steward.
Define the details of the cities, such as their approximate map.

You can stop here. Once you know these things, you choose one city where things start. That city and kingdom must be well defined, so you have to concentrate a lot on its NPC, buildings and problems. Normally, a campaign involves traveling and interacting, so you will eventually need to refine the outside world later on. Having a rough idea of what's outside the borders of the country the characters start in allows you to define a plot, and from this plot, you can plan what kind of details you will need later on.
For inspiration, I strongly suggest you to read European history, and Italian lords families such as Medici, Savoia, Estensi, Gonzaga. There's plenty of inspiration in there.
Comment: Building one isn't hard at all. It's just time consuming. I've built a dozen... all of them well enjoyed by my players...
Comment: I agree with Stefano, I think it is hard. And frankly, I am jealous that you have build so many nice ones. :(
Comment: The trick is to prioritize what you need. My best games start with a big map, and comments like "Nihon: Pseudo-japanese here" and "Widdish Islands: pseudo european 12C", then letting players build characters that define more. That same campaign world has the "Fallen God Islands" which is mapped to look like the Hero System logo done in small islands; it's a thaumatocracy... with 4 ranks of citizens (Apprentice, Journeyman, Magus, Archmagus) and their minimum requirements, the rest of its details arose in play.
Comment: Likewise, the Burning Wheel and Burning Empires both start the typical campaign with world building; a number of other games do as well; the focus is on building just enough framework for everyone to be on the same page for character building. From that common point, just run with what you know or develop in play. I'm doing similar with Blood and Honor... it's a big paradigm shift from the very montessori-esque prepared sandbox mode I started with for several less successful worlds. The best worlds grow by making it up as you need it, not by pre-game prep.
Answer: Here's what I did:

Have a bunch of adventuring locations ready (the more, the merrier).
Have players create their characters. Listen carefully.
Start drawing a sketchy map. Add whatever the players mention or their characters require to make sense, as well as some safe village or town or metropolis or inn.
Have them select the adventure they start with. Draw it on the map.
Play the adventure. Don't worry about the characters getting there or getting out.
If some of their characters survive, ask how they will spend their loot, if any, and whatever else they are doing when not adventuring. Develop some nearby safe settlement based on that.
Have them return to the same adventuring location or go to a different one. Continue until the session ends.
After the session, but before the next one, flesh out the setting: Add random encounter tables, draw a detailed/hex map (the sketchy one is a player map; don't feel compelled to stick to it), add more adventuring locations and think a bit about the safe places. Add tables of rumours.
Session after session, continue elaborating like this on whatever draws the attention of the player characters. Add a new adventuring location with rumours on the table to guide PCs there every now and then, but especially when the PCs start widening their area of influence.
Comment: A player can build their character around the setting, or the GM can build the setting around the player characters. Both approaches can work. (And there are other options.)
Comment: It is difficult to build the setting around the characters unless there is a high degree of coordination between the players making the characters, and at that point the GM has handed over many of the setting decisions to the players.
Comment: Yes, the players have influenced the setting much.
Comment: The character creation normally needs to come after at least a rough idea of the setting.  I would definitely have a different backstory and possibly very different characters for Forgotten Realms than I would for Eberron or an Underdark session.
Answer: I'd start with a megadungeon, and build the first few levels (about twice as far as you think the players will get in the first session, just in case), simply because they're a great way to keep a party occupied. Then fill in some general terrain around it, a village/town/city or two.
Have some areas around your core, where the various player characters come from. Do this after the players have decided their race and general background.
Build out from there with different types of landscape and monsters. Make a handful of NPCs and give them various problems based on their surroundings. Some the PCs can help, some they can't. Try to make the NPCs be more than quest-givers. Some background is good, and makes the world seem more real.
Place some dungeons occasionally, with various justifications as to what they use to be. A few crypts or cemeteries, some castles/keeps, a handful of caves, and an abandoned town should generally be enough for the starting area.
You'll need some explanation as to why there isn't a local ruler getting rid of the monsters. Various methods I've used or seen are:

There isn't a single local ruler with enough power to clear the dungeons, and the rulers don't co-operate.
The local rulers are busy with something else (war, famine, plague ect.)
There are no local rulers - the area is pretty savage or on the frontier of civilisation.
The power in the region is in the hands of people who, for various reasons, have no strong motivation to get their hands on the treasures in the dungeons. Maybe they don't use metals as currency, or they are nomads who never stop in one place long enough to go for a dungeon delve. Maybe they believe the dungeons are haunted, or simply respect the monsters enough to leave them alone.
The local ruler is getting rid of the monsters - he's hiring the PCs! This also explains why no-one bats an eyelid when the players haul some sacks of gold out of the old deserted castle - it's their job.

Make sure that as the players explore, you generate new areas of the map for them. Also, let them find new 'base camps' from where they can explore. This should come naturally from how you built your core. Make sure to have accurate maps for where all the new areas are.
After that, you have to decide where to take it. You can develop governments and nations, or wilderness and dungeons.
One important piece of advice: Don't go into detail for a region the PCs won't reach in the next few sessions. By the time they get there, your underlying situation may have changed a lot. Or they may simply keep going in the opposite direction.
Also, you don't have to balance everything. If the players know that there are some things out there they are no match for yet, they are more careful but also more motivated.
Answer: I would start with what your players want.  What do they want to play, and what story do you want to tell? When you get their input, then you can move on to more specific setting creation.
Answer: Start with the God Mythos that you want to use. Is it one that exists already, or is it your own, or a combination of the two? This then will give you the greatest culture upon your planet.
Now draw a map of your new planet, with the continents, land masses, and oceans named. Now decide how many cultures are on your planet, and then place them. Also create one unique culture that you and others won't recognize where you got it from.
Now how magical of a world do you want? How many suns and moons do you want?
Don't do the earth, reason being that it's too restricting on what you can and can't do, for history has already done this for you!
Now you are on your way and the rest will flow from you. Remember the old books you read; use them as examples to stay away from. You can use a small percentage from foreign works — just have your own ideas so outnumber the borrowed ones that it shows. It shows you liked that concept and thus why you included it; but don't do this to often, otherwise it looks like all you know how to do is borrow from others. (The book Dinotopia did this too much, and that cheapened it.)
Also create a list of rules alterations to give to the players from the start.
Now have fun and create.
Comment: Please consider revising your answer with grammar, spelling, and formatting improvements.
Comment: If you continue to post unedited stream-of-consciousness answers, you ***will*** keep getting downvoted. That's just the reality. Nobody else here is so careless with how they write; we expect basic writing skills from all users. If nobody can read, or wants to read, what you are posting, then it's just making the page worse. We expect answers to improve the page, not make it worse. We are actually pretty forgiving, since we have users from all over the world who might not have English as their first language, but this writing has been orders of magnitude below even our lenient standards.
Comment: Start with deities? Planetary bodies? How about starting with the peoples and how they interact with each other. Unless the PC's are going to space, it's people that they will be interacting with.
Comment: It's getting downvoted because it's hard to read and has no structure. It might sound great in your own head, but what you write is all anyone can judge by, and what is written here is a mess.
Comment: Here, I've edited. [Click this link to see how I changed it.](http://rpg.stackexchange.com/posts/47730/revisions?inline=true) I added paragraph breaks between ideas, I used English punctuation and  spacing (tip: if you think you need a semicolon (`;`), stop: you *don't* need a semicolon), and moved related ideas so that they're together in the same paragraph. I fixed run-on sentences by using periods where sentenced ended, commas and conjunctions where they continued, and semicolons, em-dashes, or colons where there are related but separate sentences. I used a spell checker.


what could cause a scraping noise after tire rotation

Question: After having one tire replaced, and the tires rotated, drove out of the shop immediately to a grrr (rubbing/grinding) sound momentarily, once per tire rotation.  I noticed the "back" tires have pretty low clearance to their encasing, perhaps there's something wrong there? (the front ones are kind of worn on the inside rim, as well, maybe its just a "normal wear" pattern issue)?  It sounds as if the tread is being worn away but if I get above like 30 it sounds like my tires going to disintegrate ;|
Answer: After taking it back to the shop, the tech. diagnosed it as "the new back tire inside rim wheel weights are rubbing" (apparently they didn't rub when those tires were in the front).  So rebalance the rear wheels (i.e. new wheel weights) and I'm back in business.
Update: got this again at a different date, even after doing a balancing.  I just told the guy about it and he "did something" (bent them in more) and it works.  Guess there's not a lot of clearance in my vehicle (Accord) for rear inside wheel weights...
Comment: Rubbing to what, exactly?
Comment: Was the tire shop happy with the wear that you could see?
Comment: @IhavenoideawhatI'mdoing I'm not sure though there wasn't a lot of clearance between the tire and the inside of the vehicle and I assume that's what was rubbing (the wheel weight against something).  It sure sounded like it was rubber hitting the frame though (like when you have a bicycle with its tire out of alignment) but guess it was just the wheel weights.  Also sounded like if I were to hit 60 my tire would explode (got louder with higher rpm's)
Comment: We have had tape type weights rub on the brake calipers. Especially if they are stacked in layers. Easy to fix.


How can I make Loadtime-AspectJ to work in applet

Question: Since AspectJ LoadTime-Weaving needs to load the JVM with an agent/it's own classloader - is there a way to load/make changes in the user's JVM from my applet? or maybe just before loading the applet (with a parent applet?)
Comment: Did you find a way how to married LTW and signed jars?
Comment: As per Chris R's answer I understand that classloading is an issue, but what about using the javaagent option?
Answer: It might be possible to add a weaving agent after the JVM is started, see:
How can I add a Javaagent to a JVM without stopping the JVM?
Answer: I'm afraid you'll be completely out of luck there.  According to the Sun docs on applet classloaders, a "web browser uses only one class loader, which is established at start-up. Thereafter, the system class loader cannot be extended, overloaded, overridden or replaced. Applets cannot create or reference their own class loader" (emphasis mine).
You will probably have more success with compile-time weaving on this problem, unless there's some reason why you can't do that.
If the applet is signed, however, you might be able to work around this.  AspectJ is not really clear on what its requirements are by way of Java Security.  I'd get on the AspectJ mailing list and ask.


Can 32-bit Linux use all 4 GB of RAM without a PAE kernel?

Question: Will I benefit from the 32-bit PAE-enabled Linux kernel over the 32-bit non-PAE kernel in a server that has exactly 4GB of ram (and 'pae' in the cpuid flags)? Will the system be able to use all 4GB of ram without a PAE kernel, or will some of the memory go idle?
Answer: Yes, you will need to enable PAE to see all 4GB of RAM. Whilst a 32Bit CPU should in theory be able to use up to 4GB of RAM without PAE, the problem with this is that it requires all 32bits of the address bus to use the 4GB, leaving nothing left for things like graphics cards. So with Non PAE systems, you will get less than 4GB.
Enabling PAE will get round this.
Comment: It would be excellent to get a source on this assertion...
Answer: You would need the PAE enabled kernel to see the 4gb of RAM, yes.  Although there is a lot of debate as to seeing the additional memory through hacks like PAE provides any advantage.
Actually Jeff Atwood made a great post about this very issue: Dude where's my RAM
Comment: +1 for the tried-and-true "Google the Joel/Jeff archives" s*.com answering technique...
Answer: I assume you want to "reclaim" the lost memory that devices use?
Now remember, physical memory is not the same as virtual address space. That is, each individual program will still only be able to use 2GB. However, more of them may be able to run without swapping.
Also remember that PAE addressing takes more page table/page directory bookkeeping, so you lose some memory to that. Probably much less than the devices used to take.
Answer: Yes, you will be able to use most if not all of the 4GB of RAM.  See this Stackoverflow posting for a more in-depth discussion of PAE (amongst other things)


How do I install Bumblebee?

Question: I have just installed Ubuntu 12.04 LTS and noticed that the battery life drastically lower than it was in Windows due to the fact that Optimus was disabled. After some search I have found the Bumblebee project, but I was not able to install it. The problem is as follows the command sudo apt-get install bumblebee bumblebee-nvidia does not work and the output is as follows:
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package bumblebee
E: Unable to locate package bumblebee-nvidia

I have tried many things, but since I am a new user I might be missing a key point. Previous commands:
sudo add-apt-repository ppa:bumblebee/stable
sudo add-apt-repository ppa:ubuntu-x-swat/x-updates

seem to work without any problems, but "sudo apt-get update" gives the following output,
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ precise/partner i386 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems

I am really confused about the situation and unable to take any action, help is greatly appreciated. Thanks
Answer: Open a terminal and run the following command:
sudo rm -rf /var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-i386_Packages

and then run:
sudo apt-get update

You can then try installing bumblebee:
sudo apt-get install bumblebee bumblebee-nvidia

Comment: Thanks for the advice, I have tried it yet it did not work. Do you have any other suggestions?

How do I install Bumblebee?


What happened at the end of The Grey?

Question: I am confused, what happened at the end of The Grey (2011)? Did Ottway die or did he manage to survive?
Comment: There's a scene after the credits that could help you with deciding who survived, but regardless it's one of those movies where you have to decide for yourself
Comment: I think it's obvious both of them died because,don't you think you would hear noises if either of them died?
Comment: he had small whiskey or brandy bottles from the plane crash taped to his hands and broke off the tops to make them pointy and very sharp . anyway a stupid movie why didn't they just stay in the fusilarge of the plane create a fortress plus having all that steel they could have made weapons and kill off the pack like duh!!!!
Answer: I think the ending is intentionally ambiguous, so each member of the audience can draw their own conclusion.  Even if Ottway kills the Alpha, will the rest of the pack let him survive?
If you watched past the credits, you saw that there was a very short (maybe two seconds) scene where we see Ottway and the Alpha wolf after they fight.  They're both alive, but badly injured.  Ottway's head is resting on top of the wolf's body.  Since both are so badly injured, I think it's unlikely that either one of them will survive.
Comment: I didn't know about that short scene as I didn't watch past the credits. Thanks for your answer.
Answer: It's symbolic:  honor your life and confront your fears.  The whole movie was about his ambivalence about living after his wife died.  He fought the enemy honoring "life" and symbolically, he won. That's my take.
Answer: Its almost certain that after someone or something kills the alpha of a pack, then the other wolves back off, praise, or even make them the new leader of their group. Because the alpha was lying weakly on the bed of snow at the brief scene after the credits, it should be obvious that he was killed or in the middle of dying. Otherwise, he'd undoubtedly be eating John and so would the others. Meanwhile, John is lying and resting his head on the side of the black alpha wolf. We're not certain if he's dead or if he survived, but the one thing we know is that the wolf is dead. One thing I can say about the way the wolf died was by the dagger John held and the broken glasses he wrapped around his hand (which looked to be some sort of medicine tube). John must have known something about the glasses because he was a huntsman after all, maybe containing poison to kill off the wolves. Either way the wolf was dead and as for John, its really up to you to figure that out. Odds are, he was sitting there thinking and praying judging the way the director casted him always in deep thought.
Comment: Sorry, I chuckled a little. The glass was small bottles of alcohol from the service cart on the plane. It wasn't medicine or poison (although I suppose some would call alcohol either of these).
Answer: I think the ending is fairly obvious, if you recall toward the beginning of the film Ottway shoots a wolf trying to attack the drillers. While the injured wolf is dying in the snow Ottway hovers over it and places his hand on the wolfs chest, the entire time we are clearly seeing the final labored breaths of the dying animal which is very similar to the scene at the end of the movie. Its pretty clear they both died, unless Ottway was pooped and decided to spoon with the alpha for a bit before returning to his aimless wandering through the Alaskan wilderness.
Furthermore this scenario would never happen since pack alpha's rarely do any of the killing, however they do in conjunction with the beta's decide who eats first.
Also, wolves are absolutely timid around humans, most documented fatalities have been children during the 18th and 19th century in North America. Although there are circumstances that would cause a wolf to attack, its very rare - I think shark and bear attacks are more common compared to wolves. The idea that these wolves would hunt these men down one by one like velociraptors is far-fetched unto itself but certainly makes for great cinema.
Answer: Live and die on this day... the wolf died, Liam lived.
Otherwise the wolf would have been eating him and his buddies would have joined in.
Either that way, or Liam found the meaning of life on the same day he died.
Answer: My take: He's alive and hopes for survival in the end. His face is towards sky. He still hopes that God exists and will send someone to rescue him or at least those purses would be collected. After all, those purses were so much valuable to them. It wouldn't make sense they'll go waste.

What happened at the end of The Grey?


Keras difference beetween val_loss and loss during training

Question: What is the difference between val_loss and loss during training in Keras?
E.g.
Epoch 1/20
1000/1000 [==============================] - 1s - loss: 0.1760, val_loss: 0.2032

On some sites I read that on validation, dropout was not working.
Comment: What you read about dropout is probably that, when dropout is used (i.e. `dropout` is not `None`), dropout is only applied during training (i.e. no dropout applied during validation). As such, one of the differences between validation loss (`val_loss`) and training loss (`loss`) is that, when using dropout, validation loss can be lower than training loss (usually not expected in cases where dropout is not used).
Answer: val_loss is the value of cost function for your cross-validation data and loss is the value of cost function for your training data. On validation data, neurons using drop out do not drop random neurons. The reason is that during training we use drop out in order to add some noise for avoiding over-fitting. During calculating cross-validation, we are in the recall phase and not in the training phase. We use all the capabilities of the network.
Thanks to one of our dear friends, I quote and explain the contents from here which are useful.

validation_split: Float between 0 and 1. The fraction of the training
  data to be used as validation data. The model will set apart this
  fraction of the training data, will not train on it, and will evaluate
  the loss and any model metrics on this data at the end of each epoch.
  The validation data is selected from the last samples in the x and
  y data provided, before shuffling.
validation_data: tuple (x_val, y_val) or tuple (x_val, y_val,
  val_sample_weights) on which to evaluate the loss and any model
  metrics at the end of each epoch. The model will not be trained on
  this data. This will override  validation_split.

As you can see
fit(self, x=None, y=None, batch_size=None, epochs=1, verbose=1, callbacks=None, validation_split=0.0, validation_data=None, shuffle=True, class_weight=None, sample_weight=None, initial_epoch=0, steps_per_epoch=None, validation_steps=None)

fit method used in Keras has a parameter named validation_split, which specifies the percentage of data used for evaluating the model which is created after each epoch. After evaluating the model using this amount of data, that will be reported by val_loss if you've set verbose to 1; moreover, as the documentation clearly specifies, you can use either validation_data or validation_split. Cross-validation data is used to investigate whether your model over-fits the data or does not. This is what we can understand whether our model has generalization capability or not.
Comment: This is misleading because it does not have to be about `cross-validation`
Comment: Would you elaborate?
Comment: @GreenFalcon Should the validation loss include the penalization (e.g. $\ell_1$ norm) we impose on the training loss?
Comment: You can, but the easier solution is to add them when you want to create the layers of your model. You can use `kernel_regularizer` and `bias_regularizer`. You can access l1 through `tf.keras.regularizers.l1`
Answer: When fitting a model, you have the option to specify a portion of the training dataset that is not trained upon. This is separate from the test dataset.
The "val" in val_loss stands for "validation." It's a shame they didn't spell it out.
model.fit(validation_split=0.1)
# By default, this float is `0.`

Or you can explicitly provide the data to model.fit(validation_data=<see soruce code below>). This would seem to be a good idea if you want a stratified (equally distributed) validation set.
training.py

The use case for this is knowing when your model is appropriately fit to your dataset. Otherwise, you are just looking back and forth at the loss and accuracy of your train and test set wondering if it is balanced.


Import Product Image Sort Order Value Using Magmi Or Other Import Tool

Question: I am looking to import multiple product images into Magento using Magmi, however I cant seem to find a way to import the product image sort order attribute along with the image. Does anybody know the easiest way to import product image positions via CSV using Magmi or dataflow profiles or any other tool?
Answer: The image processor is required if you wish to import images against your products. This plugin has several advanced features that are explained below.

This document refers to Image Attributes Processor Version 1.0.25
Base Images
The three base images can be imported by using the attribute names image, small_image and thumbnail
sku,image,small_image,thumbnail
00001,/00001.jpg,/00001small.jpg,/00001thumb.jpg
00002,/image1.jpg,/image2.jpg,/image3.jpg

The images will be imported from the folder defined in the "Image search path" setting shown in the configuration screen (entered after you enable the plugin)
Image search path
The "Image search path" field specifies the folder that your original images are stored in. The files are copied from here to the media/catalog/product image folders during the import process. This search path can be relative or absolute.

if you enter a path that does not include a leading forward slash, the value will be prefixed with the "Filesystem Path to magento directory" setting shown at the very top of the Magmi configuration screen (next to the database settings)

This normally contains the value "../.."
If you look at the two screenshots shown above, this will give a combined search path of ../../media/import
This search path is relative to your Magmi home folder (and not the Magento home folder). The image names included in your CSV file should be prefixed with a forward slash. They will directly appended to the end of the search path derived above
Absolute server path
Alternatively you can include a full server path for the images. To do this, include a leading forward slash when you enter the "Image search path" in the configuration screen.

/var/www/media/import

When you include a leading forward slash, the "File system path" is not appended and the raw value you enter will be used instead.
Note : The path does not need to be part of your Magento directory structure. For example, the path could be /tmp – or any other location on your server hard drive.
More Column Headers
sku
description
image
attribute_set
weight
media_gallery
type
tax_class_id
qty
store
price
is_in_stock
name
thumbnail
visibility
att_eby_title
small_image

Comment: Thanks for your reply Keyul. Your answer really helped me and with a couple of tests I worked out that Magmi will import each product image in the order that they are specified in the spreadsheet. All I had to do was put the products images in the spreadsheet in the order I wanted them to appear on the product page and it worked! :-)
Comment: @ Keyul Shah : is it possible images import from other server using " Image search path " ,


what magnification is required to see jupiter, saturn, venus and mars with a 50mm refractor scope with f/12 ratio and 600mm focal lenth

Question: i have a beginner telescope of 50mm and want to see planets it is arefractor with f/12 ratio and two eyepieces of 5mm and 10mm and i want to see mars, Jupiter, Saturn and venus. my max zoom ix 120x and focal length is 600mm
Comment: Both of your eyepieces should be fine. Start with the 10mm, and when you have got used to that, switch to the 5mm.
Comment: @Mick the 5mm is pushing the scope a bit too far. If it's a very high quality refractor, it might work, though the exit pupil is going to be hair-thin anyway. The 10mm should be fine, I guess.
Answer: Venus, Mars, Jupiter, and Saturn are visible with your eyes, so a telescope and magnification are not required to see them. Depending on the quality of the telescope, the magnification will show you some details.
Venus - you will be able to see the phase.
Mars - for several months every 26 months, you will be able to see some dark markings and a polar cap.
Jupiter - you will see the cloud bands and 4 of its moons.
Saturn - you will see its rings and moon Titan.
Enjoy the view!
Comment: You won't see any features on Mars with 50 mm of aperture, especially if it's a "beginner telescope".
Answer: The 10 mm ocular should work fine. It will give you 60x of magnification.
The 5 mm ocular is probably a bit too much for this scope. You can definitely try it, but the expectation here is that the image will be a bit too washed out. With 50 mm of aperture you can't really expect to push magnification much above 100x (twice the aperture in mm), and even at around 100x it would work only if it's a high performance instrument. But, like I said, try and see what happens.
What you can see in 50 mm of aperture:
You will see the phases of Venus. It will look like the Moon, just very tiny. This is best done when Venus is at the greatest distance from the Sun, and then it will look like a disk cut in half.
Jupiter - you will definitely see the disk. Seeing the equatorial belts will be more challenging, but it should be doable; it may take a few attempts if it doesn't work on first try. Jupiter is low contrast and it's hard to see its features. Let the image float through the field of view, relax and just take it in; after a few minutes your brain adapts to the view and starts perceiving more details.
Jupiter's moons are definitely visible, like 4 tiny stars that seem to follow the planet around. Sometimes some of them are hidden, so don't be surprised if you can't see them all.
Saturn's ring is clearly visible. You won't see details such as the Cassini division, but the ring itself will be shown across the planet's disk.
The Moon is an excellent target for telescopes of all sizes, and there's a lot to explore there.
Mars will probably not show a lot of details in 50 mm of aperture. Anyway, this planet is only worth observing for a few weeks around each opposition, which happens once every two years (plus a few weeks). At best you will resolve Mars as a tiny brick-red disk, but I doubt you'll see terrain features. But go ahead and give it a try; when the Hellas Basin is full of fog, or frosted over, it's very bright, so in a small aperture it might be perceived as a white speck of light on one side of the disk.
(I'm actually kind of curious myself if this would work. I'll give it a try next time around, since I have a few 50 mm doublets to play with.)

It's important to focus the instrument well before using it. E.g. point it at the Moon and adjust the focus until the image is as sharp as possible. You can also focus on stars - adjust focus until the image of the star is as small as it gets. You can also adjust focus on whatever object you're currently observing.


Translation for "Good Riddance"

Question: I'm looking for a phrase in German that can equate to the English phrase "Good riddance," a very sarcastic way of saying goodbye to someone/something that you won't actually miss. Is there a way to translate this with the proper negative connotation, or is there really no equivalent phrase? I can't find very much information about phrases like these with "hidden meanings," in a sense, so it'd be great to know if there is a phrase or why one doesn't exist.
Comment: Perhaps "Auf nimmerwiedersehen"?
Answer: As Hagen wrote in a comment, you should use nimmer, which is a old form of nie mehr and niemals. Some dialects still use it nowadays, in others it's only used in fixed expressions as

Auf Nimmerwiedersehen!/Auf Nimmer!

Other common expressions with nimmer:

auf Nimmerwiedersehen weg sein/verschwunden sein
nie und nimmer
an St. Nimmerlein/zum St. Nimmerleinstag
der Nimmersatt
nimmermehr
Comment: A side note to "St. Nimmerlein", as it might not be intuitive to non-native speakers: Back before calenders where in common use, often church holidays were used to denote dates. "Die Zinsen sind fällig an Johanni", "the interest (to the loan) is due on St. John's Day". The "Johanni" is a latin genitive, "(the day) of St. John".

"St. Nimmerlein" is a fictional, tongue-in-cheeck saint. To say something'll happen "an St. Nimmerlein" basically expresses that it'll probably _never_ happen.
Answer: Other than the already mentioned phrases with "nimmer", you could say

Lass' Dich nicht aufhalten.

That translates roughly to "Don't let anything stop/delay you", but has a stronger connotation of "Would you please go already?". The "lass" is a shortened "lasse", the imperative of "(zu-)lassen".

Translation for "Good Riddance"


Pakistani asylum seekers in Europe

Question: If someone pakistan citizens have life sentence or life penalty in his home country mean pakistan because he is did murder of one person  then he can apply for asylum in europe and how many chance for qualify then he have all type of avidence me FIR
Answer: The chance of qualifying for asylum will vary greatly depending on the circumstances.  Being sought on murder charges is probably unlikely to help unless the person has good evidence that the charges are unjustified.
If the charges are in fact justified then the asylum claim will probably not succeed.  For example, the 1951 refugee convention does not apply to anyone

...with respect to whom there are serious reasons for considering that ... he has committed a serious non-political crime outside the country of refuge prior to his admission to that country as a refugee;

However, the decision on the asylum claim will be made by the country in which he applies for asylum, under that country's domestic law.  The chance of success therefore will also vary depending on the country where asylum is sought.
Comment: While being technically correct, I don't see how Pakistan would not file an international arrest warrant for people who are **convicted** murderers and on the run.
Comment: Anecdotal evidence, I have to look up this film again. Some reporters wanted to do a piece about young men fleeing from Afghanistan. They found two, and followed their way through Iran and Turkey. Then, at the Turkish west coast, one of them was missing. They followed the remaining man to Paris. Later, they found out the other young man was charged for murder in his home country, Afghanistan, and the police in Turkey knew about that, so they arrested him and brought him back into an Afghan prison.
Comment: @Janka sure, but the existence of an international arrest warrant wouldn't change anything. If the host country judged that the charges constituted persecution, they would grant asylum and not honor the warrant. Otherwise, they'd return the person to Pakistan even in the absence of a warrant (unless the person faced the death penalty; EU countries won't extradite people unless there is an assurance that the death penalty will not be imposed).
Comment: I posted the anecdote to show up the most obvious obstacle. You had to reach a European country first.
Comment: @Janka that is quite true.  I assumed that reaching the country was implicit in "can he apply for asylum in Europe," but it is not necessarily so.  If he cannot reach Europe, he cannot apply for asylum there.

Pakistani asylum seekers in Europe


Error while opening Software Center and Update Manager in Xubuntu

Question: Using Xubuntu 12.
I can't open either the Software Center or Update Manager. I'm a complete novice!
I get the following error:

Failed to execute command "/usr/bin/software-center %u".
Failed to execute child process "/usr/bin/software-center" (No such file or directory)

I tried all I can think of by update via Synaptic package Manager  but nothing I've done works.
I've the CD  but now I'm used to this and I don't want to do a clean install and lose all my files etc.
Can a repair be done? or can it be repaired with the CD?
I'm not that good with computers but absolutely love Xubuntu?
Please make my day and tell me it can be solved!
Edit: Some outputs which may help.
alan@alan-Aspire-2930:~$ cd /usr/share/software-center/; ls | grep ^software-center$
software-center

it means there is software-center and is not deleted.
alan@alan-Aspire-2930:/usr/share/software-center$ sudo ln -s '/usr/share/software-center/software-center' '/usr/bin'
[sudo] password for alan:
ln: failed to create symbolic link `/usr/bin/software-center': File exists
alan@alan-Aspire-2930:/usr/share/software-center$

it means symbolic link also exists. It is very strange because when you run software-center it says (No such file or directory) !!!
Answer: cd /usr/share/software-center/
ls | grep ^software-center$ does this yield any output? if yes then only the symbolic link is deleted from /usr/bin/.
to create symbolic link again,
sudo ln -s '/usr/share/software-center/software-center' '/usr/bin'

if this doesn't help
try reinstalling sofware-center. It seems like python script of software center has been deleted or moved.
edit >
try sudo apt-get install software-center


Test if GeoIP is enabled and working correctly?

Question: Is there an easy way to test if GeoIP is enabled and working correctly?
Comment: I don't understand your comment, if xDB is disabled then how are you testing for GeoIPs?
Answer: You should be able to setup a test file to test if the GeoIp service is working correctly.  I'd recommend following Solution 3 in the Sitecore support issue below:
https://kb.sitecore.net/articles/798498
Basically you need to drop code like the following on your server.  Ideally in a location under the /sitecore path to protect just anyone from accessing the page.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TestIp.aspx.cs" %>
<%@ Import Namespace="Sitecore.Analytics.Lookups" %>

<!DOCTYPE html>

    <title></title>

    <form id="form1" runat="server">

        <asp:TextBox ID="TextBox1" runat="server" Width="229px"></asp:TextBox>

        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="GetInformartionByIP" Width="234px" />

        <asp:ListBox ID="ListBox1" runat="server" Height="314px" Width="557px"></asp:ListBox>

    </form>

Comment: Naim, your question asks if there is a way to test if Geo IP is enabled and working. I believe this answer adresses this question, don't you?
Comment: Hi thank you for the reply. i tried solution #3 but i am getting the following error "Null ids are not allowed. Parameter name: endpoint". xdb is disabled but GeoIp should still be working.
Comment: Hi Mark, yes but still did not solve my problem, i am still not sure whats wrong with the GeoIp for the site in hands. the sitecore testing page is throwing an exception too.
Answer: although Dylan's answer is correct but I would like to add few more points here -
if you still receiving incorrect information?

Check whether the correct IP information is stored in the Analytics database
Sitecore 7.5 – Sitecore 8.x: the "GeoIps" collection, Collection database (MongoDB)
Sitecore 6.4.1 – Sitecore 7.2: the "GeoIps" table, Analytics database (SQL)

If incorrect Geo location information stared for a given IP, deleted
that incorrect IP info from the GeoIps table/collection and do an IIS
reset.
You have to change the IP address into hash format.

Check correct Geo information will be cached/stored again in the next
request
Comment: I will note this is something that he should look into if he finds that what I describe above is returning valid data.  Because GetInformationByIP will make a direct request to the Geo IP Provider and will not use the various caching and analytics data storage methods that you are describing above.  But good information.
Comment: Hi, thank you for your answer but the xdb is disabled.


Visualizing elemental rotations using Euler angles in Matlab

Question: I'd like to visualize elemental rotations using Z-Y-X convention in Matlab. If you'd like to follow me exactly, I'll be refering to a paper Quadrotor Dynamics and Control by Randal Beard.
The base coordinate frame,  $F^v$, is called the vehicle frame (page 6). It is a right-handed cartesian frame of reference. The unit vectors in $F^v$ are $x^v, y^v, z^v$ which can be visualized in Matlab using the below script:
x_v = [1;0;0]; %Define unit vectors in vehicle frame
y_v = [0;1;0];
z_v = [0;0;1];
o_v = [x_v'; y_v'; z_v']; %Convert to quiver3 compliant form
quiver3(zeros(3,1), zeros(3,1), zeros(3,1), o_v(:,1), o_v(:,2), o_v(:,3)) %Draw the frame

I have written a function to create a Direction Cosine Matrix from Euler angles, as defined on page 9 of the aforementioned paper:
function dcm = RPY_2_DCM(roll, pitch, yaw)
  cR = cos(roll);  sR = sin(roll);
  cP = cos(pitch); sP = sin(pitch);
  cY = cos(yaw);   sY = sin(yaw);

  dcm = [cP*cY          cP*sY          -sP;
         sR*sP*cY-cR*sY sR*sP*sY+cR*cY sR*cP;
         cR*sP*cY+sR*sY cR*sP*sY-sR*cY cR*cP];
end

Drawing the vehicle-1 $F^{v1}$ frame as a rotation around $z^v$ by yaw angle with the below script works fine (vehicle frame in blue, vehicle-1 frame in green):
yaw = pi/6;
x_v1 = RPY_2_DCM(0,0,yaw)*x_v; %Draw vehicle-1 coordinate frame obtained by right-handed rotation of F_v around z_v
y_v1 = RPY_2_DCM(0,0,yaw)*y_v;
z_v1 = RPY_2_DCM(0,0,yaw)*z_v;
o_v1 = [x_v1'; y_v1'; z_v1'];
quiver3(zeros(3,1), zeros(3,1), zeros(3,1), o_v1(:,1), o_v1(:,2), o_v1(:,3))

Now, I'd like to rotate vectors in $F^{v1}$ around $y^{v1}$ axis of vehicle-1 by adding:
pitch = pi/6;
x_v2 = RPY_2_DCM(0,pitch,0)*x_v1;
y_v2 = RPY_2_DCM(0,pitch,0)*y_v1;
z_v2 = RPY_2_DCM(0,pitch,0)*z_v1;
o_v2 = [x_v2'; y_v2'; z_v2'];
quiver3(zeros(3,1), zeros(3,1), zeros(3,1), o_v2(:,1), o_v2(:,2), o_v2(:,3))

But instead of rotating around $y^{v1}$ I obtain a rotation of $F^{v1}$ around $y^v$ (see the picture below, $F^{v2}$ in red). What am I doing wrong?
Answer: A bit late, but anyway maybe my answer can help other people.
You want to perform rotations about rotating axes (intrinsic rotations), you can get the same result by inverting the order of rotations and perform the rotations about the fixed axes (extrinsic rotations), so if you want to perform intrinsic rotations about the Z axis, then about the new Y axis and finally about the new X axis you can rotate about the x axis, then about the y axis and finally about the z axis.
Answer: Your rotation matrices will be in the wrong order the way you do it! Mathematically its M1*M2*M3*V with M1,M2,M3 being the FIRST second third rotation matrix and V a vector. So you see the first transformation is the last multiplication on the vector! In your example of your second transformation you do M2*M1*V ... wrong order... wrong result...


Is there a Javascript client for Ethereum, like Geth?

Question: Ethereum's Github has ethereumjs-lib.  It appears to be a collection of modules, but is it also a client like Geth?  If so, how can one run this Javascript client?
Answer: Yes, there are 3 official clients in Golang, C++ and Python. And there are 4 unofficial clients in Java, Haskell, JavaScript and most recently Rust.
To answer your question, the full node client implementation in JavaScript is the node-blockchain-server of the ethereumjs project.
The node-blockchain-server aims to provide a full Ethereum node implementation. It is in a pretty rough state at the moment, but at least can download the blockchain.
In oposite to other client implementations, for JavaScript you need to add a couple of libraries to get a fullstack client. Check out keythereum for managing keys and ethereumjs-tx for creating transactions with them.
The full list of libraries (23) in the ethereumjs project can be found on their homepage.
Comment: node-blockchain-server says "It doesn't do state transitions".  Not clear what that means.  Also, can you send it transactions?
Comment: No, updated my answer.
Comment: Looks like the answer to this is "not yet".  If/when mentioning "need to add a couple libraries", I think it would be better to describe that more ;)
Comment: Can you scan the ethereum blockchain with these?


The agent of the infinitive in a perception context

Question: The question is on how the "agent of infinitive" slot may be filled for this syntactic structure:  with a form of direct object, or indirect object, or either.

[Agent of verb of perception] + [agent of infinitive] + [verb of perception] + [object of infinitive] + [infinitive]

One set of examples come from this Web page.

Je les entends le casser
  (I hear them breaking it)
  Je le regarde l'écrire
  (I'm watching him write it)
  Je le sens la caresser
  (I feel it caressing it)

--in which the slot is filled with what is ordinarily called a "direct object"--les and le.  (Never mind whether they are direct objects here).
The other example is from La porte étroite by Andre Gide, as follows:

Dès le vestibule, j'aperçus Alissa ; elle semblait m'attendre et vint aussitôt vers moi. Elle portait au cou, dans l'échancrure de son corsage clair, une ancienne petite croix d'améthyste que je lui avais donnée en souvenir de ma mère, mais que je ne lui avais pas encore vu mettre. Ses traits étaient tirés et l'expression douloureuse de son visage me fit mal.

--in which the slot is filled with an "indirect object"--lui.  (Again, maybe not an indirect object here.)
I believe this lui is filling the same syntactic slot as les and le in the other examples.  For example, les are heard but do the breaking.  In the same way, lui is seen but does the wearing (mettre).  Therefore, I can only see these possibilities.

The top three examples are wrong, and the Gide clause is right.
The three examples are right, and Gide is wrong.
All four are correct, and each has the only form of pronoun it can for the agent of infinitive.  There is a principle to explain why the top three must have les and le (and not leur or lui) while Gide must have lui (and not la).
All four are correct, and you get a choice in this type of context and can go with either le etc. (the "direct" form) or lui etc. ("indirect").  In this case, there might be other principles to explain why one form or another is preferable.

The question is:

Which of the above four possibilities is right?
If 3, please also explain what the principle is.
If 4, please say something about whether one form or another is preferable and why.

This question is related to this other from me, which I believe was rather poorly formulated. If anyone sees a logistical issue, I will be happy to delete the old question as repetitive, or merge this one into that, or whatever is appropriate.  Thank you.
Answer: C'est l'objet de la thèse (2006) de Fabrice Marsac intitulée «
Les constructions infinitives régies par un verbe de perception ». Normalement disponible ici (en espérant que le lien soit permanent) :

https://www.theses.fr/2006STR20060

Pages numérotés 16/17/18, il y a des références et une explication.
Comment: J'ai pas le temps d'ajouter un résumé là tout de suite. Plus tard, ou bien si quelqu'un veut bien se donner la peine…


Why is the human body hair not uniformly colored?

Question: Most of my body hair is black however my lip hair is light brown/blonde the rest of my beard region is black. Since hair color is genetic what causes this?
Answer: The hairs you mention are also called "androgenic hairs", meaning their growth and pigmentation is influenced by androgens. These include pubic hair, the hairs on the breast and shoulders (almost exclusively for men) and the beard.
It seems, that these hair bulbs have different sensibilities (number and expression of androgen receptors) so they react differently to androgen levels. This includes balding, pigmentation, growth and so on.
These articles should be a good starting point, if you want to dive deeper into the topic:

Androgen actions on the human hair follicle: perspectives.
Mechanism of action of androgen in human hair follicle.
Answer: I've heard it mentioned that gene dosage is implicated in this. Gene dosage is the number of the alleles present in the cell.
Comment: Could you give some references for this ?


How small could an orbital rocket be?

Question: To what extent might a booster designed to place an extremely light weight "micro" satellite with radio transmitter,  say 100 grams for the sake of argument,  be scaled down before factors such as increased aerodynamic drag on smaller objects,  mass ratios etc.  make such a venture impossible ?  Has anyone done speculative calculations for such as project ?
Comment: Launching from earth or from a plane ?
Do you want the satellite to remain in orbit for  hours ? days ? years ?

This will have a noticeable impact. And yes, calculations have been made.
Comment: We've had some questions a bit like this in the past, though not exact duplicates. The only one I can find right now is [this one (FIFA soccer ball)](http://space.stackexchange.com/questions/9543/how-much-thrust-to-launch-a-regulation-size-fifa-soccerball-into-orbit) but I know there are others somewhere... this may provide some interesting information anyway.
Comment: Just for clarity, are we to assume that you mean an orbit around the *Earth*?
Comment: @Andy I remember one too, but I don't remember there being an answer there - just a comment that it's drag that's going to be key to finding an answer. This question here really starts from that concept and moves further forward towards the existence of an attempt to actually calculate it.
Comment: Thanks for references and answers. This is essentially a kind of broad thought experiment involving a classic launch from ground level to LEO for whatever length of time qualifies as earth orbit.
Comment: Added the SS-520-4, which hasn't launched from Uchinora yet (was delayed) but counts in my book, even if the launch fails somehow.
Comment: Scott Manley's [How Small Can You Make An Orbital Rocket?](https://www.youtube.com/watch?v=m1bZO16em2c)
Answer: In general there's a minimum size of rocket that can place nothing other than itself in orbit (because of the energy requirements to accelerate the rocket's own parts to orbital velocity while lifting it to orbital altitude--at  mostly the same time or problems occur).  There are diminishing returns as the payload sizes gets smaller and you asymptotically approach the smallest possible rocket given the technologies you apply to it, which leads to a couple preliminary conclusions:

Existing small launchers will end up being pretty good models of what the limits are
Being a secondary payload is generally much cheaper than flying primary on a small rocket, so small rocket development hasn't taken off, so we haven't seen a lot of real exploration of the limits of small rocketry; you're usually stuck with thought experiments

That said, there have been a few papers on this, so I'll share what I've found, minus frankly distressing amounts of link rot.  I want to say I've seen a study at least once, too, but am having trouble finding one in my notes.  The motivations are typically putting up payloads the size of cubesats or smaller, e.g. http://www.news.cornell.edu/stories/2014/04/cracker-sized-satellites-launch-orbit
I came across a lot of this a few years ago while toying around with the idea of an orbital rocket that could be transported inside a typical 42-foot semi trailer.  That never became a design or paper, but maybe some day.

Dimotakis et. al concluded in 2000 that a 100lbm payload, which would be in the nanosatellite weight class, could be put into LEO for $300,000 per launch with an aircraft-launched two- or three- stage chemical rocket.  https://fas.org/irp/agency/dod/jason/leo.pdf  (I think that conclusion's nonsense, but it sure looks like they got paid for that paper and there certainly were companies thinking of doing exactly that for a while, but I think the price of being a secondary payload has dropped since then...)

A Smithsonian Air&Space article primarily about Mars Sample Return concurs with the drag limitations stated in the comments:

A terrestrial rocket has to push through a plug of air equivalent to a 30-foot column of water, and physics dictates that the smallest vehicle capable of moving all that atmospheric mass without paying a penalty in momentum is about 30 feet long.
Read more: http://www.airspacemag.com/space/the-one-pound-problem-718812/#zZldMZJXdaAdsFOL.99

There are several places I've heard that the Japanese Lambda 4S is the "smallest ground based launch vehicle to put a satellite into orbit" (quoted from the link soon to follow).  http://orbitalaspirations.blogspot.com/2011/10/japanese-lambda-4s-launcher.html does a good job breaking down the rocket equation math for the launcher.  I'd imagine its numbers could be beaten by actually having guidance (which it didn't!) and swapping out the solid rockets for more efficient motors after the first stage, but there probably isn't a ton of margin to win.  She's about 10 tons and 55 feet long.

Vector Space Systems is working on Vector-R, a 50kg to LEO launcher, at 12m tall x 1.2m diameter, 5000 kg design dimensions, though those figures change from page to page in the site...
http://vectorspacesystems.com/technology-4
http://vectorspacesystems.com/technology-5

Rocket Labs' Electron is 16x1.2m for 150kg to a 500km sun-synchronous orbit.  Somewhat more payload and to a higher orbit,  similar-ish size  https://www.rocketlabusa.com/

JAXA is planning to launch the SS-520-4, 9.54m x 0.52m, 2600kg at launch, lofting 3kg of 3U cubesat to (for TRICOM-1) an orbit of 180kmx1500km.  All per http://spaceflight101.com/ss-520-4-smallest-orbital-rocket-set-for-launch/  This is based on a sounding rocket, and I'd expect any orbital rockets at this size to be similar--sounding rockets with very small upper stages added to them.

Astra's Rocket 3 family is 11.6m long, placing it solidly in the same class as the other rockets listed here.  The SS-520-4 beat it to making a successful orbital launch (and is also smaller), and none of the Rocket 3 launches have been entirely successful as of early 2021, but I think it deserves to be listed.
Comment: I like this very thorough answer - I've just added [this supplemental answer](http://space.stackexchange.com/a/19794/12102) - feel free to edit it or just absorb the content into your answer if you like (in that case I'd just delete it). Also I noticed the Orbital Aspirations 2016 post [The Race to Build a Smaller Rocket](http://orbitalaspirations.blogspot.tw/2016/08/the-race-to-build-smaller-rocket.html) links to the [Science Friday Article](http://www.sciencefriday.com/segments/the-race-to-build-a-smaller-rocket/) of the same name.
Answer: This is just an addendum to @ErinAnne's thorough answer above, there is a new update in Spaceflight 101:

Experimental Launch of World's Smallest Orbital Space Rocket ends in Failure

While they have called it the "World's Smallest Orbital Space Rocket", so far it hasn't put it's payload into orbit yet.

above: SS-520-4 rocket ready for launch. From here, Photo: JAXA

above: SS-520-4 rocket. From here, Image: JAXA

SS-520-4 is a three-stage solid-fueled rocket standing 9.54 meters tall, measuring 52 centimeters in diameter and weighing in at 2,600 Kilograms – smaller and lighter than any previous ground-based orbital launch vehicle. It is based on the SS-520 sounding rocket design, modified with a small third stage tasked with injecting a payload into Low Earth Orbit.

above: TRICOM-1 in Launch Configuration. From here, Photo: JAXA

above: Person with TRICOM-1 for scale - in this case Professor Hiroto Habu of the Japan Aerospace Exploration Agency. Image from here.
Comment: The launch worked this time!
http://spaceflight101.com/japan-ss-520-5-launch-success/
Comment: @ErinAnne Yay! I've asked another question about the launch [here](https://space.stackexchange.com/q/24754/12102). It's a pretty amazing feat to put a satellite into orbit with such a small launch system!
Answer: I'm no rocket scientist, but I have it from two real rocket scientists that no launcher under about one metric tonne can get anything to orbit, at least if it has to start from the Earth's surface. Air launch can theoretically help, though, if it can bypass a lot of the atmosphere. There were some experiments back in the late 1950s at China Lake with multi-stage solids launched from fighter jets. They might have put small payloads into orbit, but at the time, they lacked the telemetry and tracking to verify orbit. Back then, it was hard to make anything practical with such small payload mass limits, so the approach was abandoned. Those limits aren't what they used to be, though -- significantly functional satellites fit in the cubesat format and perhaps smaller. CubeCab is trying this fighter-plane air launch approach again, planning to exploit the F-104's flight ceiling (in excess of 50,000 feet, with some versions going much higher) and launching one 3U cubesat at a time. Mach 2 isn't a very big fraction of orbital velocity, but it also helps a little. I'm not sure how big CubeCab's stack is, but it's probably much lighter than 1 metric tonne.
Answer: One force which makes launch to orbit difficult is aerodynamic force, primarily drag.  Drag is directly related to the Aspect Ratio of the rocket, which is its length divided by its diameter.  The Aspect Ratio determines the aerodynamic reference surface area, and like a sailboat, the longer and thinner the rocket the better.  Attached is a drag profile for a typical ascent which I've plotted from CFD simulation of a 42" diameter launch vehicle using Matlab.
To complete the answer, realize the mass ratio (initial mass/final mass) will determine the delta-V that the rocket can attain.  Initial mass includes the structure and payload and propellant.
The required delta-V for a mission is determined by the destination orbit, drag, and launch site (angular velocity of earth adds to delta-v). The required delta-V dictates the mass of propellant required. The mass of propellant and its density dictates the required volume of the tanks.  Since a rocket is mostly tanks, the volume of the tanks dictates the size of the rocket. The designer needs to decide the diameter of the tanks, and voila! The length of the rocket is determined.
Going back to my original concern, a design with a high Aspect Ratio, that is a long rocket with small diameter, will face less drag in its flight.  The plot shows that drag for the vehicle I modeled sees maximum drag at around Mach 1.3, which is the point of maximum dynamic pressure (Max Q). This is also the point of maximum structural loading.  However, a long, thin rocket having high Aspect Ratio may not have the structural integrity to fly through Max Q without damage and/or loss of control.  So this factor would be the limit on how small the diameter of a rocket could be.
I believe the Black Brandt sounding rocket has the largest Aspect Ratio of any operational vehicle, but it is a suborbital rocket.
References

Arthur Greensite, Analysis and Design of Space Vehicle Flight Control Systems
Hill and Peterson, Mechanics and Thermodynamics of Propulsion

How small could an orbital rocket be?


Rickshaw electric conversion

Question: Is it possible to buy a traditional pedal rickshaw and stick an electric bike conversion kit on it? The rickshaw I've seen is the type when the rider is at the rear and so has two wheels at the front and one at the rear.

Comment: Electric rickshaws are quite common in touristic places allover the world.
Comment: If you're in Europe, any more than a 250W motor *even on a cargo bike* requires all sorts of things that normal cycling doesn't ([summary article](https://www.cyclingweekly.com/news/product-news/new-e-bike-category-ups-power-1000-watts-396471).  However 250W pedelec delivery bikes are useful, even in the hilly city where I live, as are un-assisted bakfiets for transporting children.  It would certainly be a nice way to take the kids to school, on the right roads (which are rare round here)
Comment: Its not going to be cheap - you'll need to look at the total load weight and size the motor accordingly,  Remember its an assist not a replacement for pedalling.   Separately, if you're doing this as a business there may be other legally-imposed limits and requirements, like a taxi/bus driver's licence, lighting, seat belts/lights/helmets etc.
Comment: Yes the Baofeng BB looks great but is too powerful for the UK, think I will give this daydream a miss. I like the idea in theory but given the roads, the expense of it and regulations I don't think it's practical. This was the video that got me thinking about it BTW: https://www.youtube.com/watch?v=O6Ti4qUa-OU
Answer: Tadpole-style trikes with one wheel in back are quite easy to electrify.
You can either use a rear hub motor or a bottom bracket motor. Given the high startup torque requirements with rickshaws and thus the desirability of low gearing and a range of gears, I'd recommend a bottom bracket motor such as a Bafang BB - the only concern is if there's enough clearance to mount the bottom bracket motor around that frame. This allows you to have a pretty good range of gears using a rear derailleur or internal geared hub such as a Rohloff on back.
You can reprogram a BB motor controller so that max assist is limited to 250 watts or max assist speed is limited to 30 kph or whatever your local laws are. Proving that your assist is limited in such a fashion to a constable that is trying to write you a ticket is another matter.
Hub motors that have two or more gears are available but their long term reliability is still unknown — and even with gears, hub motors unfortunately don't have great starting torque.

Rickshaw electric conversion