Allen sits, but Pierce, Celtics still roll over Bucks

BOSTON (AP) -The Boston Celtics are unbeatable at home this season, even with just two of their new Big Three.

Paul Pierce scored a season-high 32 points and Kevin Garnett had an easy 15 with seven rebounds on Friday night, and the Celtics overcame Ray Allen 's absence to beat the Milwaukee Bucks 104-82 and match the franchise record with a 12-0 start at home.

''I wanted to be a little bit more aggressive,'' Pierce said. ''Especially with Ray out, (I wanted) to pick up some of the slack and get us going.''

Rajon Rondo scored 17 with eight assists for Boston, which also won its first 12 home games in 1984. Led by the Big Three of Larry Bird, Kevin McHale and Robert Parish, that team went to the '85 NBA finals.

Garnett, Pierce and Allen are leading the Celtics' efforts to hang another banner in the new Garden, but they are without Allen for a game or two because of a sore right ankle. Instead, Tony Allen started and scored 11 with four steals while holding Michael Redd to seven points.

''I thought Tony Allen was a spark tonight guarding Mike,'' Bucks coach Larry Krystkowiak said. ''I think that's one of the reasons Tony was in the lineup, to bring his energy.''

Redd is averaging 24 points this season, and he hadn't scored seven points or fewer since 2004.
''Tony was awesome,'' Celtics coach Doc Rivers said. ''Mike Redd, he's an All-Star. That's a tough matchup. If someone looked at the stat sheet you'd see 3-for-7. But if you had a game ball, you'd probably give it to Tony Allen .''

Garnett played just 29 minutes for the Celtics, who pulled away when they outscored Milwaukee 32-15 in the third quarter. Boston will try to set the team record for home wins to start a season Wednesday against Detroit.

Mo Williams scored 14 for the Bucks, Bobby Simmons had 11 and Yi Jianlian scored 10.
The Celtics turned a five-point deficit with 3:22 left in the second quarter into a 46-44 halftime lead. But it was in the third when they really pulled away.

They scored 12 consecutive points early in the third to turn a 49-48 Bucks lead into a 60-49 advantage, then added a 10-0 run near the end of the quarter to make it 78-57.

''The lead was eight and all of a sudden it got to 20,'' Redd said. ''So we've got to play near-perfect basketball to beat them at their home.''

For the second straight game - but just the second time this season - the Celtics were without their regular starting five. Allen is expected to miss a game or two with a sore right ankle that he has been trying to play through for eight games.

Notes: The Celtics are undefeated when leading after three quarters, but they've lost both games they trailed after three. ... Boston is 7-0 on Friday nights. ... Rondo was scoreless in Wednesday night's game against Sacramento. ... The Bucks fell to 2-11 on the road and 2-6 in December. ... Pierce was 9-for-9 from the line, and the Celtics were 26-for-28.

Operation of Machine gun

All machine guns follow a cycle:

‧ Removing the spent cartridge through an ejection port.
‧ Cocking the trigger mechanism so the weapon can be fired again.
‧ Loading the next round into the firing chamber. Usually spring tension or a cam forces the new round and bolt back into the firing chamber.

A mechanism makes the firing pin fire the cartridge, activating the ejection and reloading steps. The cycle repeats. This full cycle takes a fraction of a second and can thus occur many times per second. The operation is basically the same, regardless of the means of activating these mechanisms. Some examples:

‧ Machine pistols and submachine guns (like the World War II "grease gun,"MAC-10 or the Uzi) are usually blowback operated.

‧ Most assault rifles and squad automatic weapons are gas operated. Some weapons, such as the AR-15/M16, integrate the piston with the bolt. Others, such as the AR-18 and AK patterns, attach the piston to a bolt carrier that unlocks and operates the bolt.

‧ A recoil actuated machine gun uses the recoil to first unlock and then operate the action. Heavy machine guns, such as the M2 .50 and Browning .50, are of this type. These can be recognized by a large cocking lever needed to feed the first round.

‧ An externally actuated machine gun uses an external power source, such as an electric motor or even a hand crank to move its mechanism through the firing sequence. Most modern weapons of this type are called chain guns in reference to their driving mechanism. Gatling guns and revolver cannon have several barrels or chambers on a rotating carousel and a system of cams that load, cock, and fire each mechanism progressively as it rotates through the sequence. The continuous nature of the rotary action allows for an incredibly high cyclic rate of fire, often several thousand rounds per minute. Not all chain guns use multiple barrels or chambers, though. Chain guns are less prone to jamming than a gun operated by gas or recoil, as the external power source will eject misfired rounds with no further trouble. This is not possible if the force needed to eject the round comes from the round itself. Chain guns are generally used with large shells, 20 mm in diameter or more, though some, such as the M134 minigun, fire smaller cartridges. They offer benefits of reliability and firepower, though the weight and size of the power source and driving mechanism makes them impractical for use outside of a vehicle or aircraft mount.

Heavy machine guns are often water cooled or have interchangeable barrels, which must be changed periodically to avoid overheating. The higher the rate of fire, the more often barrels must be changed and allowed to cool. To minimize this, most air-cooled guns are fired only in short bursts or at a reduced rate of fire.

Not all machine guns strike the primer in the same way. In blowback machine guns, the act of seating the round also fires the round. In gas operated and recoil-operated guns, a separate step in the firing sequence is needed to strike the round. In a progressive-fire gun, the firing pin is cycled by cams. In some automatic cannon, the primer is fired electrically.

U.S. Marines and their M240G at Camp Hansen, Okinawa

In weapons where the round seats and fires at the same time, mechanical timing is essential for operator safety, to prevent the round from firing before it is seated properly. This is especially important in weapons like the 40 mm grenade launcher, where high explosives are present in the rounds being fired.

Machine guns are controlled by one or more mechanical sears. When a sear is in place, it effectively stops the bolt at some point in its range of motion. Some sears stop the bolt when it is locked to the rear. Other sears stop the firing pin from going forward after the round is locked into the chamber.

Almost all weapons have a "safety" sear, which simply keeps the trigger from engaging.

Operation of BB Gun

BB guns can use any of the operating mechanisms used for air guns; see the powerplant technology section of the air gun article. However, due to the limited accuracy and range inherent in the BB gun, only the simpler and less expensive mechanisms are generally used.

Since nearly all BBs used today are steel, it is common to find BB guns that use magnets in their loading mechanisms. Since the BB is too hard to be swaged to the bore size, magnets are often used to hold the BB at the rear of the barrel--otherwise, the BB would simply roll out of the barrel if it were held at a downward angle.

The traditional, and still most common powerplant for BB guns is the spring piston type, usually patterned after a lever action rifle or a pump action shotgun. The lever action rifle was the first type of BB gun, and still dominates the inexpensive youth BB gun market. The Daisy Model 25 BB gun, modeled after a pump action shotgun with a trombone pump action mechanism, dominated the low price, higher performance market for over 50 years. Lever action models generally have very low velocities, around 275 ft/s, a result of the weak springs used to keep cocking efforts low for use by youths. The Daisy Model 25 BB gun typically achieved the highest velocities of its day, ranging from 375 ft/s to 450 ft/s. Lever action guns often have huge ammunition capacities; one of Daisy's early lever action models held 1000 BBs, in contrast to the Daisy Model 25 which held only 50 BBs. The ammunition in the lever action BB guns is gravity fed, such that the gun must be held at the proper angle when cocked to load the ammunition. The ammunition in the Daisy Model 25, on the other hand, is spring loaded, and no shift in gun angle is required to reload another BB.

Multi-pump pneumatic guns are also common--many youth oriented pneumatic pellet guns provide the ability to use BBs as a cheaper alternative to lead shot. These guns have rifled barrels, but the hard, slightly undersized BBs don't swage or obturate to fit the barrel, so the rifling may not impart a significant spin. These are the type of guns that will benefit most from using precision lead BB shot. The pneumatic BB gun attains much higher velocities than the traditional spring piston types. One interesting use of a pneumatic BB gun is in the calibration of ballistic gelatin, which is done by measuring the penetration of a steel BB at a velocity of about 600 ft/s (180 m/s).

The last common type of power for BB guns is pre-compressed gas, most commonly the 12 gram CO2 powerlet. The powerlet, invented by Crosman, is a disposable bottle containing 12 grams of liquid carbon dioxide, which evaporates to form a gas to propel the BB. These are primarily used in pistol BB guns, and unlike spring-piston or pneumatic types, these are capable of rapid fire. A typical CO2 BB pistol uses a spring-loaded magazine to feed BBs, and a double action trigger mechanism to chamber a BB and cock the hammer. The hammer strikes a valve hooked to the CO2 source, which releases a measured amount of CO2 gas to fire the BB. Velocities of CO2 powered BB pistols are moderate, and drop off as the temperature in the CO2 source drops, due to changes in the vapor pressure. Many CO2 BB guns are patterned after popular firearms, and can be used for training as well as recreation.

Some gas-powered BB guns use a larger source of gas, and provide machine gun-like fire. These types are commonly found at carnivals, and have also been used to train antiaircraft gunners. A popular commercial model was the Larc M-19, which ran off 1 pound (454 g) canisters of Freon-12 refrigerant. These types have very simple operating mechanisms, based on a venturi pump. The gas is released in a constant stream, and this is used to suck the BBs up into the barrel at a very high rate--advertisements for the Larc M-19 claimed a rate of fire of 3000 rounds per minute.

Civil engineering

Civil engineering

Civil engineering is a professional engineering discipline that deals with the design and construction of the physical and natural built environment, including works such as bridges, roads, canals, dams and buildings.[1][2][3] Civil engineering is the oldest engineering discipline after military engineering,[4] and it was defined to distinguish it from military engineering.[5] It is traditionally broken into several sub-disciplines including municipal engineering, environmental engineering, geotechnical engineering, structural engineering, transportation engineering, water resources engineering, materials engineering, coastal engineering,[4] surveying, urban planning, and construction engineering.[6]

History

Engineering has been an aspect of life since the beginnings of human existence. Civil engineering might be considered properly commencing between 4000 and 2000 BC in Ancient Egypt and Mesopotamia when humans started to abandon a nomadic existence, thus causing a need for the construction of shelter. During this time, transportation became increasingly important leading to the development of the wheel and sailing. The construction of Pyramids in Egypt (circa 2700-2500 BC) might be considered the first instances of large structure constructions. Other ancient historic civil engineering constructions include the Parthenon by Iktinos in Ancient Greece (447-438 BC), the Appian Way by Roman engineers (c. 312 BC), and the Great Wall of China by General Meng T'ien under orders from Ch'in Emperor Shih Huang Ti (c. 220 BC).[6]

Until modern times there was no clear distinction between civil engineering and architecture, and the term engineer and architect were mainly geographical variations referring to the same person, often used interchangeably.[7] In the 18th century, the term civil engineering began to be used to distinguish it from military engineering.[5] The first self-proclaimed civil engineer was John Smeaton who constructed the Eddystone Lighthouse.[6][4]
The first degree in Civil Engineering in the United States was awarded by Rensselaer Polytechnic Institute in 1835.

Sub-disciplines

In general, civil engineering is concerned with the overall interface of human created fixed projects with the greater world. General civil engineers work closely with surveyors and specialized civil engineers to fit and serve fixed projects within their given site, community and terrain by designing grading, drainage, pavement, water supply, sewer service, electric and communications supply, and land divisions. General engineers spend much of their time visiting project sites, developing community consensus, and preparing construction plans. General civil engineering is also referred to as site engineering; a branch of civil engineering that primarily focuses on converting a tract of land from one usage to another. Civil engineers typically apply the principles of geotechnical engineering, structural engineering, environmental engineering, transportation engineering and construction engineering to residential, commercial, industrial and public works projects of all sizes and levels of construction.

Construction engineering

Construction engineering involves planning and execution of the designs from transportation, site development, hydraulic, environmental, structural and geotechnical engineers. As construction firms tend to have higher business risk than other types of civil engineering firms, many construction engineers tend to take on a role that is more business-like in nature: drafting and reviewing contracts, evaluating logistical operations, and closely-monitoring prices of necessary supplies.



Environmental engineering

Environmental engineering deals with the treatment of chemical, biological, and/or thermal waste, the purification of water and air, and the remediation of contaminated sites, due to prior waste disposal or accidental contamination. Among the topics covered by environmental engineering are pollutant transport, water purification, sewage treatment, and hazardous waste management. Environmental engineers can be involved with pollution reduction, green engineering, and industrial ecology. Environmental engineering also deals with the gathering of information on the environmental consequences of proposed actions and the assessment of effects of proposed actions for the purpose of assisting society and policy makers in the decision making process.

Environmental engineering is the contemporary term for sanitary engineering, though sanitary engineering traditionally had not included much of the hazardous waste management and environmental remediation work covered by the term environmental engineering. Some other terms in use are public health engineering and environmental health engineering.

Geotechnical engineering

Geotechnical engineering is an area of civil engineering concerned with the rock and soil that civil engineering systems are supported by. Knowledge from the fields of geology, material science and testing, mechanics, and hydraulics are applied by geotechnical engineers to safely and economically design foundations, retaining walls, and similar structures. Environmental concerns in relation to groundwater and waste disposal have spawned a new area of study called geoenvironmental engineering where biology and chemistry are important.[14][15]

Some of the unique difficulties of geotechnical engineering are the result of the variability and properties of soil. Boundary conditions are often well defined in other branches of civil engineering, but with soil, clearly defining these conditions can be impossible. The material properties and behavior of soil are also difficult to predict due to the variability of soil and limited investigation. This contrasts with the relatively well defined material properties of steel and concrete used in other areas of civil engineering. Soil mechanics, which define the behavior of soil, is complex due to stress-dependent material properties

Hydraulic engineering

Hydraulic engineering is concerned with the flow and conveyance of fluids, principally water. This area of civil engineering is intimately related to the design of pipelines, water distribution systems, drainage facilities (including bridges, dams, channels, culverts, levees, storm sewers), and canals. Hydraulic engineers design these facilities using the concepts of fluid pressure, fluid statics, fluid dynamics, and hydraulics, among others. Water resources engineering is concerned with the collection and management of water (as a natural resource). As a discipline it therefore combines hydrology, environmental science, meteorology, geology, conservation, and resource management. This area of civil engineering relates to the prediction and management of both the quality and the quantity of water in both underground (aquifers) and above ground (lakes, rivers, and streams) resources. Water resource engineers analyze and model very small to very large areas of the earth to predict the amount and content of water as it flows into, through, or out of a facility. Although the actual design of the facility may be left to other engineers.

Materials science

Civil engineering also includes elements of materials science. Construction materials with broad applications in civil engineering include ceramics such as Portland cement concrete (PCC) and hot mix asphalt concrete, metals such as aluminum and steel, and polymers such as polymethylmethacrylate (PMMA) and carbon fibers. Current research in these areas focus around increased strength, durability, workability, and reduced cost.

Structural engineering

Structural engineering is concerned with the structural design and structural analysis of buildings, bridges, and other structures. This involves calculating the stresses and forces that act upon or arise within a structure, and designing the structure to successfully resist those forces and stresses. Resistance to wind and seismic loadings, especially performance near resonant frequencies, which affect the overall stability of a structure, are major design concerns. Other factors such as durability and cost are also considered. In addition to design of new buildings, structural engineers may design a seismic retrofit for an existing structure to mitigate undesirable performance during earthquakes.

Surveying

Surveying is the process by which a surveyor measures certain dimensions that generally occur on the surface of the Earth. Modern surveying equipment, such as EDM's, total stations, GPS surveying and laser scanning, allow for remarkably accurate measurement of angular deviation, horizontal, vertical and slope distances. This information is crucial to convert the data into a graphical representation of the Earth's surface, in the form of a map. This information is then used by civil engineers, Contractors and even realtors to design from, build on, and trade, respectively. Elements of a building or structure must be correctly sized and positioned in relation to each other and to site boundaries and adjacent structures. Civil engineers are trained in the methods of surveying and may seek professional land surveyor status.

Transportation engineering

Transportation engineering is concerned with moving people and goods efficiently, safely, and in a manner conducive to a vibrant community. This involves specifying, designing, constructing, and maintaining transportation infrastructure which includes streets, canals, highways, rail systems, airports, ports, and mass transit. It includes areas such as transportation design, transportation planning, traffic engineering, urban engineering, queueing theory, pavement engineering, Intelligent Transportation System (ITS), and infrastructure management.

3D models

3D Modeling

3D models (the product of modeling procedures) are often created with special software applications called 3D modelers when not describing the title of a professional who uses the software to produce 3D models. Being a collection of data (points and other information), 3D models can be created by hand, algorithmically (procedural modeling), or scanned. Though they most often exist virtually (on a computer or a file on disk), even a description of such a model on paper can be considered a 3D model.


A 3D model of a Mangalore from the film The Fifth Element in the 3D modeler LightWave, shown in various manners and from different perspectives

3D models are widely used anywhere 3D graphics are used. Actually, their use predates the widespread use of 3D graphics on personal computers. Many computer games used pre-rendered images of 3D models as sprites before computers could render them in real-time.

Today, 3D models are used in a wide variety of fields. The medical industry uses detailed models of organs. The movie industry uses them as characters and objects for animated and real-life motion pictures. The video game industry uses them as assets for computer and video games. The science sector uses them as highly detailed models of chemical compounds. The architecture industry uses them to demonstrate proposed buildings and landscapes. The engineering community uses them as designs of new devices, vehicles and structures as well as a host of other uses. In recent decades the earth science community has started to construct 3D geological models as a standard practice.

A model is not technically a graphic until it is visually displayed. Due to 3D printing, 3D models are not confined to virtual space.


Modeling processes

There are three popularly used means by which to represent a model:

Polygonal modeling - Various vertices on an xyz grid are mapped out. The vertices are connected in a linear fashion to form a polygonal mesh. Used for example by Maya 3d.

NURBS modeling - Curves are formed by defining control points and attaching a "weight" to each one. The curve follows (but does not necessarily interpolate) the points. Increasing the weight for a point will pull the curve closer to that point. NURBS are particularly suitable for organic modelling. Used for example by Rhino3d.


Splines&Patches modeling - Curves which define the surface directly (Splines) used for example by Hash Animation:Master.

The modeling stage consists of shaping individual objects that are later used in the scene. There are a number of modeling techniques, including:

constructive solid geometry

implicit surfaces

subdivision surfaces

Modeling can be performed by means of a dedicated program (e.g., Maya, 3DS Max, Blender, Lightwave, Modo) or an application component (Shaper, Lofter in 3DS Max) or some scene description language (as in POV-Ray). In some cases, there is no strict distinction between these phases; in such cases modelling is just part of the scene creation process (this is the case, for example, with Caligari trueSpace and Realsoft 3D).

Complex materials such as blowing sand, clouds, and liquid sprays are modeled with particle systems, and are a mass of 3D coordinates which have either points, polygons, texture splats, or sprites assign to them.


Representation

The Utah teapot, one of the most common models used in 3D graphics education
Because the appearance of an object depends largely on the exterior of the object, boundary representations are common in computer graphics. Two dimensional surfaces are a good analogy for the objects used in graphics, though quite often these objects are non-manifold. Since surfaces are not finite, a discrete digital approximation is required: polygonal meshes (and to a lesser extent subdivision surfaces) are by far the most common representation, although point-based representations have been gaining some popularity in recent years. Level sets are a useful representation for deforming surfaces which undergo many topological changes such as fluids.

The process of transforming representations of objects, such as the middle point coordinate of a sphere and a point on its circumference into a polygon representation of a sphere, is called tessellation. This step is used in polygon-based rendering, where objects are broken down from abstract representations ("primitives") such as spheres, cones etc, to so-called meshes, which are nets of interconnected triangles. Meshes of triangles (instead of e.g. squares) are popular as they have proven to be easy to render using scanline rendering. Polygon representations are not used in all rendering techniques, and in these cases the tessellation step is not included in the transition from abstract representation to rendered scene.

Scene setup

Scene setup involves arranging virtual objects, lights, cameras and other entities on a scene which will later be used to produce a still image or an animation.

Lighting is an important aspect of scene setup. As is the case in real-world scene arrangement, lighting is a significant contributing factor to the resulting aesthetic and visual quality of the finished work. As such, it can be a difficult art to master. Lighting effects can contribute greatly to the mood and emotional response effected by a scene, a fact which is well-known to photographers and theatrical lighting technicians.

It is usually desirable to add color to a model's surface in a user controlled way prior to rendering. Most 3D modeling software allows the user to color the model's vertices, and that color is then interpolated across the model's surface during rendering. This is often how models are colored by the modeling software while the model is being created. The most common method of adding color information to a 3D model is by applying a 2D texture image to the model's surface through a process called texture mapping. Texture images are no different than any other digital image, but during the texture mapping process, special pieces of information (called texture coordinates or UV coordinates) are added to the model that indicate which parts of the texture image map to which parts of the 3D model's surface. Textures allow 3D models to look significantly more detailed and realistic than they would otherwise.

Other effects, beyond texturing and lighting, can be done to 3D models to add to their realism. For example, the surface normals can be tweaked to affect how they are lit, certain surfaces can have bump mapping applied and any other number of 3D rendering tricks can be applied.

3D models are often animated for some uses. They can sometimes be animated from within the 3D modeler that created them or else exported to another program. If used for animation, this phase usually makes use of a technique called "keyframing", which facilitates creation of complicated movement in the scene. With the aid of keyframing, one needs only to choose where an object stops or changes its direction of movement, rotation, or scale, between which states in every frame are interpolated. These moments of change are known as keyframes. Often extra data is added to the model to make it easier to animate. For example, some 3D models of humans and animals have entire bone systems so they will look realistic when they move and can be manipulated via joints and bones, in a process known as skeletal animation.

Compared to 2D methods

3D Photorealistic effects are often achieved without wireframe modeling and are sometimes indistinguishable in the final form. Some graphic art software includes filters that can be applied to 2D vector graphics or 2D raster graphics on transparent layers.

Advantages of wireframe 3D modeling over exclusively 2D methods include:

‧ Flexibility, ability to change angles or animate images with quicker rendering of the changes;
‧ Ease of rendering, automatic calculation and rendering photorealistic effects rather than mentally visualizing or estimating;
‧ Accurate photorealism, less chance of human error in misplacing, overdoing, or forgetting to include a visual effect.

Disadvantages compare to 2D photorealistic rendering may include a software learning curve and difficulty achieving certain hyperrealistic effects. Some hyperrealistic effects may be achieved with special rendering filters included in the 3D modeling software. For the best of both worlds, some artists use a combination of 3D modeling followed by editing the 2D computer-rendered images from the 3D model.

3D model market

There is a large and thriving market for 3D models (as well as 3D-related content, such as textures, scripts, etc.), either as individual models or large collections. Online marketplaces for 3D content allow individual artists to sell content that they have created. Often, the artists' goal is to get additional value out of assets they have previously created for projects. By doing so, artists can earn more money out of their old content, and companies can save money by buying pre-made models instead of paying an employee to create one from scratch. These marketplaces typically split the sale between themselves and the artist that created the asset, often in a roughly 50-50 split. In most cases, the artist retains ownership of the 3d model; the customer only buys the right to use and present the model.

Collections of hundreds to thousands of 3D models on CD, often royalty free, are for sale. These models include different types of people, animals, objects, plants, rocks, tools, furniture, buildings, landscapes, historical objects, cartoon characters, monsters, science fiction objects, medieval fantasy objects, etc. A person who buys such a CD can import these posable ready-made models into their computer animation program.