060070103-Rifat Yılmaz-2nd Week Definitions

Robotic Joint (Previous) GROUP: Manufacturing technology

A robot joint is a mechanism that permits relative movement between parts of a robot arm. The joints of a robot are designed to enable the robot to move its end-effector along a path from one position to another as desired.

(Nanua Singh; Systems approach to computer-integrated design and manufacturing,1996 ; pg 310)

Robotic Joint (New)

The robot arm is a serial chain of three rigid bodies called robot segments. Two neighbor segments of a robot manipulator are connected through a robot joint. The robot manipulator is consist of a robot arm, wrist and gripper (Figure 1.4)  The joint decreases the number of degrees of freedom which occur between two neighbor segments. The robot joints have only one degree of freedom and arc cither translational or rotational (Figure 1.5).

The rotational joint has the form of a hinge and limits the motion of two neighbor segments to rotation around the joint axis. The relative position of the segments is given by the angle of rotation around the joint axis. In simplified robotic models the rotational joint is represented by a cylinder.

The translational joint restricts the movement two neighboring segments to translation. The relative position between the two segments is measured as a distance. The symbol of the translational joint is a prism.

(T.Bajd, M. Mihelj, J. Lenarčič, A. Stanovnik, M. Munih, Robotics page 4-5.)

New definition is obvious than previous one. It is better one.

Fourth-Generation Language (4GL) (previous) GROUP: Software Technology

Introduction of graphical user interface, the people have started for alternative solutions, which will ease handling the large databases, and do not require excessive programming in high level language. The answer was fourth generation languages.

Structed Query Languages(SQL) , Query by Example(QBE) is considered as fourth generation languages. These languages are used to gather data from the database with visiual interface like Visual Basic(VB) Developer For Oracle, Application Program Tools (APT) for Sybase works well and requires minimum amount of efforts to query the databese.

(Introduction To Computers And C Programming, S.K Bajpai,Page49)

Fourth-Generation Language (4GL) (New)

Fourth-Generation languages (4GLs) are also sometimes called very-high-level languages. Although there is no precise definition of 4GLs, most people agree that they are nonproce­dural, closer to natural language than third-generation languages, and are much easier to use. Because 4GLs often allow programmers to create programs while writing very little code, if any, using 4GLs also results in increased productivity. A disadvantage to using 4GLs is that they can result in a greater number of program statements and less efficient object code when they are compiled into machine language. Because they use more storage space and execute more slowly, professional programmers may choose to use a third-generation language or an assembly language instead of a fourth-generation language in some instances.

Fourth-generation languages are commonly used today to access databases. For exam­ple, structured query language (SQL) is a 4GL commonly used to write queries to retrieve information from a database. Application gener­ators and some of the programs discussed earlier as tools to help facilitate program devel­opment are also sometimes considered fourth-generation languages.

One property that makes 4GLs easier to use is that they are declarative, rather than procedural like third-generation languages. This means that when you program using a 4GL. you tell the computer what to do without telling it how to do it. Consequently, much of the coding in a declarative programming language consists of mouse clicks to select instructions and issue commands to the program. However, if you want a highly cus­tomized program to do something well beyond the ordinary, you will probably need a pro­cedural language. To provide more flexibility, some software packages have both declarative and procedural components.

(Deborah Morley, Charles S. Parker, Understanding Computers: Today and Tomorrow,12^th edition, page 574)

New definition is more understandable than previous one. It is better one.

Polycodes (Previous) GROUP: Software technology

Each digit in this code (also known as chain type) has its own interpretation, which does not depend on the preceding digit. This structure tends to be relatively long, but it allows the identification of specific part attributes and is well suited to computer implementation.

(Kalpakjian S., Schmid S.R, Manufacturing Engineering and Technology 5th Edition, p. 1212)

Polycodes (New)

This is also known by many other names such as chain code, discrete code and fixed digit code. In polycode, the code symbols are independent of each other. Each digit in a specific location of the code describes a unique property of the work piece. It is easy to learn and useful in manufacturing situations in which the part functions or the manufacturing processes have to be described. An example of polycode is shown in Fig. 15.4. The length of a polycode may become excessive because of its unlimited combinational features. The numbers of mutually exclusive characteristics that can be inscribed in a 5-digit polycode are 50(10 + 10+ 10+ 10 + 10). Thus, the polycode is simple to understand and interpret, and only the limited information can be given in the code.

(K. Lalit Narayan, K. Mallikarjuna Rao, M.M.M. Sarcar, Computer Aided Design And Manufacturing, pages 356,357)

New definition is more understandable and obvious than previous one. It is better one.

Photo-Electron Emission Microscope (PEEM) (Previous) GROUP: Material Microscopy

Device for studying chemistry, grain orientation, and microstructure of flat, massive specimens using electrons emitted from the specimen’s surface under the influence of a focused beam of high-intensity ultraviolet light (penetration depth ∼10 nm). The lateral resolution of PEEM is ∼15 nm. Heating attachment to PEEM makes it suitable for inþsitu observations.

The photoelectron emission microscope (PEEM) is a microscope type that uses photons for illumination; it is a direct or “paralel” imaging technique ant it uses a so-called cathode lens as part of the microscope objective lens.

Photoelectron emission microscope is a high-contrast method that iis now being rediscovered by surface and materials scientists because of its versatility and surface sensitivity. A summary of its progress from 1930 to the present in electron microscope instrument development would usually be given in terms of tthe image resolution that has been achieved with the lastest instrument. The race started with optical microscopy, and the need for electron microscopists to justify their more copmlex instrument with better resolution than the very advanced and sophisticated optical instrument of their day. The much younger field of surface science has advanced through halfway in PEEM.

IN STIU REAL-TIME CHARACTERIZATION OF THIN FILMS (PG:227)

ORLANDO AUCIELLO

ALAN R. KRAUSS

Photo-Electron Emission Microscope (PEEM) (New)

Photo-electron emission microscopes (PEEM), a high-intensity beam of ultraviolet light is focussed by means of quartz lenses and mirrors on a small area of a surface (area in the order of 0.2 mm², energy density several W/cm²) which activates emission of relatively slow electrons. A high voltage is applied between the sample and a pierced anode facing the sample surface. These electrons, after passing the axial aperture of the anode and the magnetic lenses of a three-stage electron microscope, produce a highly magnified image on a fluorescent screen or a photographic film. Contrary to scanning electron microscopy, the light-beam cannot be focussed to a sufficiently small size, and integral image generation is used which has the advantage of small exposure times, varying with material and magnification from a tenth to a hundred seconds. The sample surface is cleaned by ion bombardment, but contamination is sometimes a problem in spite of the high vacuum in the chamber (typically 10^-10 bar).

Owing to the very small depth of information (10 nm), the high lateral resolution (< 10 nm), the excellent phase separation and the possibility for in-situ heating (high temperature study), photo electron microscopy is excellently capable for quantitative kinetic studies of changes in microstructural geometry. For example, a study by Taylor and Pollard [1982] has revealed the bonding sequence (grain-boundary movement and annihilation) during diffusion-bonding of steel under load at temperatures up to 1000°C.

But the major draw-back of PEEM has been the very high price of instrumentation.

(R.W. Cahn, Robert W. Cahn, Physical Metallurgy, pages 985,986)

New definition is more true and general  than previous one. It is better one.

Reaming (Previous) GROUP: Manufacturing Method

Reaming is used to slighlt enlarge a hole, to provide a better tolerance on its diameter, and to improve its surface finish. The tool is called a reamer , and it usually has straight flutes.

(P.Groover,Fundamentals of Modern Manufacturing third edition ,page 519)

Reaming (New)

Reaming - is a secondary machining operation for existing holes. It can provide a more accurate diameter, improved straightness, and a smoother surface finish as it slightly enlarges the hole. A rotating tool, a reamer, is used. The operation can be performed on a drill press or other drilling machine and is sometimes done by hand. Reamers normally remove 0.005 to 0.015 in (0.13 to 0.38 mm) of diameter. Reamers normally float, that is they follow the direction and location of the existing hole, but they can also be guided by bushings to slightly improve the hole's direction or location. The operation is most common with holes from 1/8 to 11/4 in (3 to 32 mm) in diameter but both smaller and larger holes can be reamed. A typical reamer is illustrated in Fig. 3B1 and the reaming operation on a lathe is shown schematically in and Fig. 3B4. Taper reamers are used for finishing tapered holes.

(James G. Bralla, Handbook of Manufacturing Process, page  94)

New definition is more understandable and obvious than previous one. It is better one.