Acronym Definition
LQNC Layered Queueing Network Center
LQNC Limited Q-Ball and Curt Cazall
LQNC Limited Qualified Nonelective Contribution
LQNC Limited Qualimetrics Network Controller
LQNC Limited Quality NonConformance
LQNC Limited Quasi-Neutrality Condition
LQNC Limited Queen's News Centre
LQNC Limited Queensland Naturalists Club
LQNC Limited Queensland Nursing Council
LQNC Limited Quick Net Connect
LQNC Layered Queueing Network Center
Queueing theory (also commonly spelled queuing theory) is the mathematical
study of waiting lines (or queues).
The theory enables mathematical analysis of several related processes, including
arriving at the (back of the) queue, waiting in the queue (essentially a storage
process), and being served by the server(s) at the front of the queue. The
theory permits the derivation and calculation of several performance measures
including the average waiting time in the queue or the system, the expected
number waiting or receiving service and the probability of encountering the
system in certain states, such as empty, full, having an available server or
having to wait a certain time to be served.
Queueing theory is generally considered a branch of operations research because
the results are often used when making business decisions about the resources
needed to provide service. It is applicable in a wide variety of situations that
may be encountered in business, commerce, industry, public service and
engineering. Applications are frequently encountered in customer service
situations as well as transport and telecommunication (note that something
called ride theory is sometimes mentioned, but it is uncertain whether it is a
valid theory or a hoax). Queueing theory is directly applicable to intelligent
transportation systems, call centers, PABXs, networks, telecommunications,
server queueing, mainframe computer queueing of telecommunications terminals,
advanced telecommunications systems, and traffic flow.
Spelling
The word queue comes, via French, from the Latin cauda, meaning tail. Most
researchers in the field prefer the spelling 'queueing' over 'queuing',[1]
although the latter is somewhat more common in other contexts.
History
Agner Krarup Erlang, a Danish engineer who worked for the Copenhagen Telephone
Exchange, published the first paper on queueing theory in 1909.
David G. Kendall introduced an A/B/C queueing notation in 1953.
Notation
Notation for describing the characteristics of a queueing model was first
suggested by David G. Kendall in 1953. Kendall's notation introduced an A/B/C
queueing notation that can be found in all standard modern works on queueing
theory, for example, Tijms.[2] The A/B/C notation designates a queuing system
having A as interarrival time distribution, B as service time distribution, and
C as number of servers. So, for instance, G/D/1 would indicate a General (may be
anything) arrival process, a Deterministic (constant time) service process and a
single server. More details on this notation are given in the article about
queueing models.
Application to telephony
The Public Switched Telephone Networks (PSTNs) are designed to accommodate the
offered traffic intensity with only a small loss. The performance of loss
systems is quantified by their Grade of Service (GoS), driven by the assumption
that if insufficient capacity is available, the call is refused and lost.[3]
Alternatively, overflow systems make use of alternative routes to divert calls
via different paths — even these systems have a finite or maximum traffic
carrying capacity.[3]
However, the use of queueing in PSTNs allows the systems to queue their
customer's requests until free resources become available. This means that if
traffic intensity levels exceed available capacity, customer’s calls are here no
longer lost; they instead wait until they can be served.[4] This method is used
in queueing customers for the next available operator.
A queueing discipline determines the manner in which the exchange handles calls
from customers.[4] It defines the way they will be served, the order in which
they are served, and the way in which resources are divided between the
customers.[4][5] Here are details of three queueing disciplines:
First In First Out – This principle states that customers are served one at a
time and that the customer that has been waiting the longest is served first.[5]
Last In First Out – This principle also serves customers one at a time, however
the customer with the shortest waiting time will be served first.[5]
Processor Sharing – Customers are served equally. Network capacity is shared
between customers and they all effectively experience the same delay.[5]
Queueing is handled by control processes within exchanges, which can be modelled
using state equations.[4][5] Queueing systems use a particular form of state
equations known as Markov chains which model the system in each state.[4]
Incoming traffic to these systems is modelled via a Poisson distribution and is
subject to Erlang’s queueing theory assumptions viz.[3]
Pure-Chance Traffic – Call arrivals and departures are random and independent
events.[3]
Statistical Equilibrium – Probabilities within the system do not change.[3]
Full Availability – All incoming traffic can be routed to any other customer
within the network.[3]
Congestion is cleared as soon as servers are free.[3]
Classic queueing theory involves complex calculations to determine call waiting
time, service time, server utilisation and many other metrics which are used to
measure queueing performance.[4][5]
Queueing networks
Queues can be chained to form queueing networks where the departures from one
queue enter the next queue. Queueing networks can be classified into two
categories: open queueing networks and closed queueing networks. Open queueing
networks have an external input and an external final destination. Closed
queueing networks are completely contained and the customers circulate
continually never leaving the network.
Role of Poisson process, exponential distributions
A useful queueing model both (a) represents a real-life system with sufficient
accuracy and (b) is analytically tractable. A queuing model based on the Poisson
process and its companion exponential probability distribution often meets these
two requirements. A Poisson process models random events (such as a customer
arrival, a request for action from a web server, or the completion of the
actions requested of a web server) as emanating from a memoryless process. That
is, the length of the time interval from the current time to the occurrence of
the next event does not depend upon the time of occurrence of the last event. In
the Poisson probability distribution, the observer records the number of events
that occur in a time interval of fixed length. In the (negative) exponential
probability distribution, the observer records the length of the time interval
between consecutive events. In both, the underlying physical process is
memoryless.
Models based on the Poisson process often respond to inputs from the environment
in a manner that mimics the response of the system being modeled to those same
inputs. The analytically tractable models that result yield both information
about the system being modeled and the form of their solution. Even a queuing
model based on the Poisson process that does a relatively poor job of mimicking
detailed system performance can be useful. The fact that such models often give
"worst-case" scenario evaluations appeals to system designers who prefer to
include a safety factor in their designs. Also, the form of the solution of
models based on the Poisson process often provides insight into the form of the
solution to a queuing problem whose detailed behavior is poorly mimicked. As a
result, queuing models are frequently modeled as Poisson processes through the
use of the exponential distribution.
Limitations of mathematical approach
Classic queueing theory is often too mathematically restrictive to be able to
model all real-world situations exactly. This restriction arises because the
underlying assumptions of the theory do not always hold in the real world.
For example; the mathematical models often assume infinite numbers of customers,
or queue capacity, or no bounds on inter-arrival or service times, when it is
quite apparent that these bounds must exist in reality. Often, although the
bounds do exist, they can be safely ignored because the differences between the
real-world and theory is not statistically significant, as the probability that
such boundary situations might occur is remote compared to the expected normal
situation. In other cases the theoretical solution may either prove intractable
or insufficiently informative to be useful.
Alternative means of analysis have thus been devised in order to provide some
insight into problems which do not fall under the mathematical scope of queueing
theory, though they are often scenario-specific since they generally consist of
computer simulations and/or of analysis of experimental data. See network
traffic simulation.
LQNC Laser Quest Net Center
Laser Quest is the name of a Canadian based indoor lasertag game based around
infrared (IR) hand held units and vests, as well as the name of the company
which operates each game center. There are over 140 Laser Quest centers
world-wide, including ones in Canada, the United States, the UK, France,
Portugal, Singapore, Costa Rica, Thailand, South Africa and The Netherlands.
Overview of Laser Tag
Main article: Laser Tag
The general aim of laser tag is to tag your opponents as many times as possible
with one's laser as possible, while avoiding being tagged oneself. The players
are equipped with infrared/laser hand held units and packs with sensors on, and
let into a large multi-level, maze-like arena filled with ramps, catwalks and
windows. In Laser Quest centers, the playing arenas are fog filled and black
light lit.
Equipment
The Laser Quest equipment is beginning to show its age when compared to the
features of newer systems. However, old, the system is tried and true. Every LQ
center is equipped with, on average, 30 "packs," "vests," or (the actual name)
ponchos, give or take some depending on the size of the arena.
The "pack" is made of a thick canvas-type material that hangs over your
shoulders. When laid out flat on a table, the vest forms a diamond shape. There
are sensors placed on various parts of the vest: the front half covering the
stomach, the rear half covering the lower back, and each shoulder.
The IR sensors are attached to PCBs, or printed circuit boards, which include
red and green LEDs that light up when the pack is active. Each PCB is housed in
a hard plastic housing commonly called a cover. (i.e. front cover, back cover,
shoulder cover) Part of each cover is made from clear plastic to allow the IR
beams from the lasers to reach the sensors while still protecting the delicate
equipment inside.
The rear PCB and the two shoulder PCBs are connected to the front PCB via flat,
eight conductor, Cat-5 cabling which is run through flexible conduit on the
pack.
The front and rear PCBs are interchangeable as long as the front/rear dipswitch
is switched correctly. Front and rear PCBs also need one extra piece called the
MPU, or microprocessing unit, to function. The front cover also contains the
vibrator motor which operates by the quick imbalanced rotation of a weighted
cylinder. The datalink is a small PCB housed in the rear cover with an antenna
wire that runs up to either one or both shoulders that allows the pack to
communicate with the LQX computer. The datalink is connected to the rear PCB.
The actual brains of the pack is kept in the HHU, or hand held unit, more
commonly known as the laser. The HHU is attached to the pack via a flat, coiled,
eight conductor, Cat-5 cable that connects to the front PCB. There are IR
sensors on the front and two sides of the HHU. Inside the HHU shell is the PCB
with sensors and lights, a speaker (to indicate the status of the pack), a
trigger, and an LCD (to display the status of the pack to the player). There is
also an MPU on the HHU PCB which is NOT interchangeable with the front and rear
MPUs. Although now sold and repaired as one piece, the IR unit and the PCB are
two separate pieces. The IR unit is what emits the visible laser your eye sees
and the invisible IR beam which "tags" the opponent's packs. The IR unit is a
metallic cylinder roughly one inch in diameter and one inch long.
The HSDU, or high speed data unit, is a device connected to LQX that
communicates with the pack wirelessly. (through the datalink on the back)
LQX is the name for the main game computer. This computer does it all: gives
mission time remaining, registers code names, activates games, runs the Member's
Terminal, and runs the Score monitor. LQX is still run on Windows 3.11 but LQ
may finally be upgrading to Windows XP.
Scoring
Laser Quest players gain points by tagging other players or by tagging the
opposing team's base. They lose points when they are tagged by other people, or
when they are caught in a trap. The number of points lost depends on where the
player hit and game settings. The scale for a typical game is as follows:
Laser: 3 points
Front: 5 points
Shoulders: 3 points
Back: 4 points
Tagging another player gains a player 10 points, no matter where the other
player is hit. Being tagged by the Marshal or (when applicable) by a trap costs
50 points. Tagging the opposing team's base (when applicable) gains a player 50
points. Players always gain more points for making a tag than they lose for
being tagged.
Players may also be awarded bonus points based on their accuracy--usually 10
points for every 1% hit rate. In other words, if a player achieved a hit rate of
10%, he or she would be awarded 100 bonus points. This is usually limited to a
maximum bonus of far less than the theoretical maximum of 1000 points in order
to prevent people tagging one person with their first attempt and then hiding
for the rest of the game.
The team score is the sum of all the individual players' scores.
Playing styles
There are a number of different recognized playing styles. They are as follows:
Profiling
This involves twisting one's body such that the side is presented to the enemy.
This makes the front and back sensors harder to hit, and completely hides one of
the shoulders.
Lifting Weights
This is one of the oldest techniques, and is used in some form in almost all
legal types. In this style, the player starts off with the "Profiling" style,
but while turned to the side, they bend at the waist, and then lean back up,
while holding the gun, tilted on it's side, far out in front of their chest.
They then can tilt the gun up and down by the back of the gun, giving great
ability to aim and confuse the opponent if used effectively. This overall motion
looks like you're lifting the gun as if it's a weight, thus, the name of the
style.
Crouching
This is self-explanatory. It has the advantage of protecting front and back
sensors, and gives an element of surprise. The shoulder sensors are very
exposed. (Illegal in tournament play)
Laying Down
This covers the front sensors but the back sensors are open for attacks from
above. Shoulder sensors are fairly safe. (Illegal in tournament play)
The Tower, AKA Dalek
Involves holding the gun above one's head. Aiming is more difficult, and this
leaves the front and back sensors very exposed. It is effective because of the
surprise, the better angle on shoulder sensors. It is also effective since many
good players instinctively aim for the gun sensor rather than the front, as the
gun sensor is usually the easiest to hit, due to the need for a player to aim.
If shoulders remain covered while a player is using this style, it is considered
illegal in tournament play.
Rowing The Boat
Involves holding the gun below one's waist and ducking down while moving it side
to side. Aiming is a bit more difficult, but one's laser is very hard to hit.
One's shoulders are also protected fairly well. It is considered illegal in
tournament play.
Game variants
The hardware and software used limit what types of games a Laser Quest center
can hold. Up to four different groups of settings can be created; it is normal
for everyone on a team to have the same settings, though this is not required.
When giving packs within a team different settings, the packs will not be
visibly different in-game.
The settings which can be altered are:
Game type: All-on-all, 2-team, 3-team
Total game time (minutes)
Number of lives: 1+, or unlimited
Number of shots: 1+, or unlimited
Downtime (seconds)
Shoulder sensors on/off
Gun sensors on/off
Bases on/off (only applies to team games)
Replenishers on/off (recharge with extra lives and shots if you run out)
Replenisher values for lives and shots
Sentinel effect on/off (recharge your own teammates)
Sentinel values for lives and shots
The number of shots used can be quite large; in certain game types, players
routinely fire 3000+ shots. This will give an accuracy rate of perhaps 5%. This
seemingly low amount is a result of constant firing and dodging, as players are
not directly penalized for missed shots.
Downtime is defined as the period of time after a player is tagged that they
remain deactivated. After the downtime has expired, the de-activated player's
pack will re-energise and they are able to play as before.
Normal games
These are offered at most Laser Quest centers. Every player has the same
settings, and the games are able to be run with different numbers of people. The
settings and tactics are considered to be less complicated than those used in
other game types.
Standard Solo Mission
Suggested settings:
Game type: All-on-all
* Total game time: 20 minutes
Lives: Unlimited
Shots: Unlimited
Downtime: 3 to 5 seconds
Shoulder sensors: On
Gun sensors: On
In this game, there are no formal teams; any player can tag any other player,
and each player is given an individual score. The game ends when the time limit
runs out. Winning is based upon final score--the player with the highest score
wins.
There are a variety of playing styles which can work in this game. Which one
works best depends on individual strengths/weaknesses, other players' tactics,
the layout of the arena etc. Some potential tactics are: sniping, constant
movement, and tailing a weaker player individual in order to gain more points.
Ironman
Suggested settings
Game type: All-on-all
Total game time: 30 minutes
Lives: Unlimited
Shots: Unlimited
Downtime: 1-3 seconds
Shoulder sensors: On
Laser sensors: On
This game is essentially a standard solo mission, albeit with a thirty-minute
timeframe.
Last man standing
Suggested settings:
Game type: All-on-all
Total game time: 15 minutes
Lives: 10
Shots: Unlimited
Downtime: 3 seconds
Shoulder sensors: On
Gun sensors: On
The last man alive is declared the winner of this game. If there is more than
one player left at the end, the game is usually declared a draw; in some
variants, however, this would result in no winner.
This game variant is similar to a standard deathmatch, with the addition of a
limited number of lives. This makes for a slightly slower, more cautious game.
Gun sensors are on, to discourage snipers.
Frenzy
Suggested settings:
Game type: All-on-all
Total game time: 15 minutes
Lives: Unlimited
Shots: Unlimited
Downtime: 1 seconds
Shoulder sensors: On
Gun sensors: On
Standard teams
Suggested settings:
Game type: Teams
Total game time: 15 minutes
Lives: Unlimited
Shots: Unlimited
Downtime: 5 seconds
Shoulder sensors: On
Laser sensors: On
Bases: Off
The game ends when the time limit runs out. Winning is based on final team
score, which is the sum of the scores of every player in that team.
This is the second-most often played game, after Standard Deathmatch. The
players are split into two or three teams, each of which has their own colour.
Friendly fire will not have any effect. Teams usually start the game in opposite
sides of the arena.
Limited life team game
Suggested settings:
Game type: Teams
Total game time: 15 minutes
Lives: 10
Shots: Unlimited
Downtime: 5 seconds
Shoulder sensors: On
Gun sensors: On
Bases: Off
The team with the last man standing wins the game. Frequently, more than one
person from the winning team will survive. If the time runs out, the game is
declared a draw, though this is not the case with all variants (see Last man
standing).
Bases
Suggested settings:
Game type: Two Teams
Total game time: 15 minutes
Lives: Unlimited
Shots: Unlimited
Downtime: 5 seconds
Shoulder sensors: On
Gun sensors: On
Bases: On
This is a standard team game with bases turned on. Because the bases score 50
points each time they are triggered, they play a central role in this game. This
can make the game much more territorial, as players try to defend their base and
attack their opponents'. One tactic is for players to camp at the opposing
team's bases. The winners are the team with the most points when the time runs
out.
Here is a short list of "Special Games".
War Of The Sentinals
Each player starts off on one of the three teams (red, green, and mixed.) Each
player starts off with 10 lives and 1000 shots. Each player can tag a team mate
and they will get a "sentinal boost" and receive one life and 50 shots (those
amounts can be changed by the laser quest marshals.) the team with the last
person wins.
Hot House
Solo game. All players are put into one tower to battle it out. The last player
standing wins.
Gladiator
Solo match. Everyone battles it out in this free for all game. The gladiator
stays out of the fight till all other players but 1 remain. he starts with 10
lives. The survivor and the gladiator then duel it till one loses.
"They Came From Above"
Team Game. One team is restricted to the top level of the arena, while the other
team is restricted to the bottom level. Ramps are legal ground up to the
mid-point (usually marked). Halfway through the match, play is paused to allow
teams to switch levels (team on top moves to the bottom and vice versa). Team
with the highest score wins.
Mortal Kombat
Solo Match/Gladiator Variant. Players have limited lives (usually 40) and
unlimited shots. One player is chosen as "Shao Khan" and kept out of main play.
Game takes place in the arena for the first five minutes of the match. After the
five minutes, play is moved to the "airlock" (pack storage) to continue. Last
man standing faces "Shao Khan" with remaining lives. Last man standing wins.
Royal Rumble
Solo Match. Players have limited lives (usually 40). All player keys are put
into a box and are drawn randomly, then activated on a suit. The first two
players enter the arena for one minute. At set intervals (usually 30 seconds or
one minute), another player's key is drawn, and they are sent into the arena.
This continues until all players are in. Last man standing wins.
Vampires
Team Match. Players on the "human" team have limited lives (usually 3). Players
on the "vampire" team have unlimited lives, but their downtime is much greater
(usually 15 seconds) and are vastly outnumbered (in a 30 player game, two are
made vampires at the start). The human players have to fend off the vampire
players for the duration of the match (20 minutes). After a human has lost all
their lives, they change over to the vampire team. The human team wins if they
still have players when time expires. The vampire teams wins by turning all of
the humans into vampires.
Jedi VS Sith
Team Match. Teams are divided on a 6:1 basis (six "Jedi" players to every "Sith"
player). Players have limited lives (Jedi with 30, Sith with 90) and minimal
downtime (1-3 seconds). Sith are sent into the arena first and are given a
minute to hide. Jedi are sent in after this period (after the play countdown has
ended). Last team with players remaining wins.
RuneScape is a Java-based
MMORPG operated by Jagex Ltd. With over nine million active free accounts and
more than one million paid member accounts, RuneScape is rated among the most
popular online games in the world. More than five million unique players access
their accounts to play RuneScape at least once per month. RuneScape offers both
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with an Internet connection and to run in an ordinary web browser without
straining system resources. One of the best website that discussed various
gamers' issues is IJFG.com IJFG.COM
Internet Junction For Gamers Internet Junction
For Gamers, Runescape Market and More IJFG.COM This site has Jokes, Pranks, Runescape and other cool games at IJFG.COM. RuneScape is set in a medieval
fantasy world, similar to "Guild Wars" or "EverQuest", where players control
character representations of themselves. As with most massive multiplayer online roleplaying games (MMORPG), there is no overall objective or end to the game.
Players explore, form alliances, perform optional tasks, and complete quests for
rewards and to build character's skills.
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RuneScape takes place in the fantasy-themed realm of Gielinor, which is divided
into several different kingdoms, regions, and areas. Players can travel
throughout the gaming world on foot, by using magical teleportation spells or
devices, or mechanical means of transportation. Each region offers different
types of monsters, materials, and quests to challenge players. Players are shown
on the screen as customisable avatars. They set their own goals and objectives,
deciding which of the available activities to pursue. There is no linear path
that must be followed. Players can engage in combat with other players or with
monsters, complete quests, or increase their experience in any of the available
skills. Players interact with each other through trading, chatting, or playing
combative or cooperative mini-games.
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