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رزفایل

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تحقیق در مورد فرزکاری 53 انگلیسی ص

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Milling is basic machining process in which the surface is generated by the progressive formation and removal of chips of material from the workpiece as it is fed to a rotating cutter in a direction perpendicular to the axis of the cutter. In some cases the workpiece is stationary and the cutter is fed to the work. In most instances a multiple- tooth cutter is used to that the metal removal rate is high, and frequently the desired surface is obtained in a single pass of the work.

The tool used in milling is known as a milling cutter. It usually consists of a cylindrical body which rotates on its axis and contains equally spaced peripheral teeth that intermittently engage and cut the workpiece (see Figure 22-4). In some cases the teeth extent part way across one or both ends of the cylinder.

Because the milling principle provides rapid metal removal and can produce good surface finish, it is particularly well- suited foe mass- production work, and excellent milling machines have been developed for this purpose. However, very accurate and versatile milling machines of a general- purpose nature also have been developed that are widely used in job- shop and tool and die work. A shop that is equipped with a milling machine and an engine lathe machine almost any type of product of suitable size.

Types of milling operation. Milling operations can be classified into two broad categories, each of which has several variations:

In peripheral milling a surface is generated by teeth located in the periphery of the cutter body; the surface is parallel with the axis of rotation of the cutter. Both flat and formed surface can be produced by this method. The cross section of the resulting surface corresponds to the axial contour of the cutter. This procedure often is called slab milling.

In face milling the generated flat surface is at right angles to the cutter axis and is the combined result of the actions of the portions of the teeth located on both the periphery and the face of the cutter. The major portion of the cutting is done by the peripheral portions of the teeth with the face portions providing a finishing action.

The basic concepts of peripheral and face milling are illustrated in Figure 22-1. Peripheral milling operations usually are performed on machines having horizontal spindles, whereas face milling is done on both horizontal-and vertical- spindle machines

Surface generation in milling. Surfaces can be generated in milling by the two distinctly different methods depicted in Figure 22-2. Note that in up milling the cutter rotates against the direction of feed of the workpiece, whereas in down milling the rotation is in the same direction as the feed. As shown in Figures 22-2 and 22-3, the method of chip formation is quite different in the two cases. In up milling the chip is very thin at the beginning, where the tooth first contacts the work, and increases in thickness, becoming a maximum where the tooth leaves the work. The cutter tends to push the work along and lift it upward from the table. This action tends to eliminate any effect of looseness in the feed screw and nut of the milling machine table and results in a smooth cut. However, the action also tends to loosen the work from the clamping device so that greater clamping forces must be employed. In addition, the smoothness of the generated surface depends greatly on the sharpness of the cutting edges.

In down milling, maximum chip thickness occurs close to the point at which the tooth contacts the work. Because the relative motion tends to pull the workpiece into the cutter, all possibility of looseness in the table feed screw must be eliminated if down milling is to be used. It should never be attempted on machines that are not designed for this type of milling. Inasmuch as the material yields in approximately a tangential direction at the end of the tooth engagement, there is much less tendency for the machined surface to show tooth marks than when up milling is used.

Another considerable advantage of down milling is that the cutting force tends to hold the work against the machine table, permitting lower clamping forces to beemployed. This is articularlyadvantageous when milling thin workpieces or when taking heavy cuts.

Sometimes a disadvantage of down milling is that the cutter teeth strike against the surface of the work at the beginning of each chip. When the workpiece has a hard surface, such as castings do, this may cause the teeth to dull rapidly.


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تحقیق در مورد فرزکاری 53 انگلیسی ص

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Psychology is an academic and applied discipline which involves the scientific study of human or animal mental functions and behaviors. In addition or opposition to employing scientific methods, psychologists often rely upon symbolic interpretation and critical analysis, albeit less frequently than other social sciences such as sociology.

A professional theorist or practitioner of psychology is called a psychologist. Psychologists study such phenomena as perception, cognition, attention, emotion, motivation, personality, behavior and interpersonal relationships. Some, especially depth psychologists, also consider the unconscious mind.a Psychologists attempt to understand the role of mental functions in individual and social behavior, while also exploring the underlying physiological and neurological processes.

Psychological knowledge is applied to various spheres of human activity including the family, education, employment, and the treatment of mental health problems. Psychology includes many sub-fields that span areas as diverse as human development, sports, health, industry, media and law. Psychology incorporates research from the social sciences, natural sciences, and humanities

The study of psychology in philosophical context dates back to the ancient civilizations of Egypt, Greece, China, India, and Persia. Psychology began adopting a more clinical[2] and experimental[3] approach under medieval Muslim psychologists and physicians, who built psychiatric hospitals for such purposes.[2]b

In 1802, French physiologist Pierre Cabanis helped to pioneer biological psychology with his essay Rapports du physique et du moral de l'homme (On the relations between the physical and moral aspects of man). Cabanis interpreted the mind in light of his previous studies of biology, arguing that sensibility and soul are properties of the nervous system.

Though the use of psychological experimentation dates back to Alhazen's Book of Optics in 1021,[3][4] psychology as an independent experimental field of study began in 1879, when the German physician Wilhelm Wundt founded the first laboratory dedicated exclusively to psychological research at Leipzig University in Germany, for which Wundt is known as the "father of psychology".[5] The year 1879 is thus sometimes regarded as the "birthdate" of psychology. The American philosopher and psychologist William James published his seminal book, Principles of Psychology[6] in 1890, laying the foundations for many of the questions on which psychologists would focus for years to come. Other important early contributors to the field include the German psychologist Hermann Ebbinghaus (1850–1909), a pioneer in the experimental study of memory at the University of Berlin; and the Russian physiologist Ivan Pavlov (1849–1936) who investigated the learning process now referred to as classical conditioning.

Starting in the 1950s, the experimental techniques set forth by Wundt, James, Ebbinghaus, and others would be reiterated as experimental psychology became increasingly cognitive (concerned with information and its processing) and, eventually, constituted a part of the wider cognitive science.[7] In its early years, however, this development was seen as a "revolution",[7] as it both responded to and reacted against strains of thought—including psychodynamics and behaviorism—that had developed in the meantime.

Psychoanalysis

From the 1890s until his death in 1939, the Austrian physician Sigmund Freud developed a method of psychotherapy known as psychoanalysis. Freud's understanding of the mind was largely based on interpretive methods, introspection and clinical observations, and was focused in particular on resolving unconscious conflict, mental distress and psychopathology. Freud's theories became very well-known, largely because they tackled subjects such as sexuality, repression, and the unconscious mind as general aspects of psychological development. These were largely considered taboo subjects at the time, and Freud provided a catalyst for them to be openly discussed in polite society. Clinically, he helped to pioneer the method of free association and a therapeutic interest in dreams.

Freud had a significant influence on Swiss psychiatrist Carl Jung, whose analytical psychology became an alternative form of depth psychology. Other well-known psychoanalytic thinkers of the mid-twentieth century included Sigmund Freud's daughter psychoanalyst Anna Freud, German-American psychologist Erik Erickson, Austrian-British psychoanalyst Melanie Klein, English psychoanalyst and physician D. W. Winnicott, German psychologist Karen Horney, German-born psychologist and philosopher Erich Fromm, and English psychiatrist John Bowlby. Throughout the 20th century, psychoanalysis evolved into diverse schools of thought, most of which may be classed as Neo-Freudian.c

Psychoanalytic theory and therapy were criticized by psychologists such as B. F. Skinner and Hans Eysenck, and by philosophers including Karl Popper. Skinner and other behaviorists believed that psychology should be more empirical and efficient than psychoanalysis, although they frequently agreed with Freud in ways that became overlooked as time passed.[8] Popper, a philosopher of science, argued that Freud's, as well as Alfred Adler's, psychoanalytic theories included enough ad hoc safeguards against empirical contradiction that the theories fell outside the realm of scientific inquiry.[9] By contrast, Eysenck maintained that although Freudian ideas could be subjected to experimental science, they had not withstood experimental tests. By the 21st century, psychology departments in American universities had become experimentally oriented, marginalizing Freudian theory and regarding it as a "desiccated and dead" historical artifact.[10] Meanwhile, however, researchers in the emerging field of neuro-psychoanalysis defended some of Freud's ideas on scientific grounds,d while scholars of the humanities maintained that Freud was not a "scientist at all, but ... an interpreter."[10]

Behaviorism

Founded in the early 20th century by American psychologist John B. Watson, behaviorism was embraced and extended by Americans Edward Thorndike, Clark L. Hull, Edward C. Tolman, and later B. F. Skinner. Behaviorism reflected a belief that the methodology behind laboratory-based animal experimentation, which was increasing in popularity as physiology grew more sophisticated, could provide useful psychosocial understanding of a type that comparatively subjective inquiries, such as psychodynamic analysis as employed by Freud or introspection as used by Wundt and James, could not.

The behaviorists shared with their predecessors a philosophical inclination toward positivism and determinism.[8] With Skinner, however, they entered into a line of thought, extending back to Austrian physicist and philosopher Ernst Mach, which held that the research methods most faithful to their scientific orientation would yield "the pursuit of tools for the control of life problems rather than a search for timeless truths".[8] The behaviorists argued that many contents of the mind were not open to scientific scrutiny and that scientific psychology should emphasize the study of observable behavior. Behaviorists focused on behavior-environment relations and analyzed overt and covert (i.e., private) behavior as a function of the organism interacting with its environment.[11] Therefore, they often rejected or deemphasized dualistic explanations such as "mind" or "consciousness"; and, in lieu of probing an "unconscious mind" that underlies unawareness, they spoke of the "contingency-shaped behaviors" in which unawareness becomes outwardly manifest.[8]

Among the behaviorists' most famous creations are Watson's Little Albert experiment, which applied classical conditioning to a human being, and Skinner's notion of operant conditioning, which acknowledged that human agency could affect patterns and cycles of environmental stimuli and behavioral responses. American linguist Noam Chomsky's critique of the behaviorist model of language acquisition is regarded by many as a key factor in the decline of behaviorism's prominence.[12] But Skinner's behaviorism has not died, perhaps in part because it has generated successful practical applications.[12] The fall of behaviorism as an overarching model in psychology, however, gave way to a new dominant paradigm: cognitive approaches.[13]

Humanism and existentialism

Humanistic psychology was developed in the 1950s in reaction to both behaviorism and psychoanalysis. By using phenomenology, intersubjectivity and first-person categories, the humanistic approach sought to glimpse the whole person—not just the fragmented parts of the personality or cognitive functioning.[14] Humanism focused on fundamentally and uniquely human issues, such as self-identity, death, aloneness, freedom, and meaning. The humanistic approach was distinguished by its emphasis on subjective meaning, rejection of determinism, and concern for positive growth rather than pathology. Some of the founders of this school of thought were American psychologists Abraham Maslow, who formulated a hierarchy of human needs, and Carl Rogers, who created and developed client-centered therapy; and German-American psychiatrist Fritz Perls, who co-founded Gestalt therapy. It became so influential as to be called the "third force" within psychology, along with behaviorism and psychoanalysis.[15] Later, positive psychology opened up humanistic themes to scientific modes of exploration.

Influenced largely by the work of German philosopher Martin Heidegger and Danish philosopher Søren Kierkegaard, psychoanalytically-trained American psychologist Rollo May pioneered an existential breed of psychology, which included existential therapy, in the 1950s and 1960s. Existential psychologists differed from others often classified as humanistic in their comparatively neutral view of human nature and in their relatively positive assessment of anxiety.[16] Existential psychologists emphasized the humanistic themes of death, free will, and meaning, suggesting that meaning can be shaped by myths, or narrative patterns,[17] and that it can be encouraged by an acceptance of the free will requisite to an authentic, albeit often anxious, regard for death and other future prospects. Austrian existential psychiatrist and Holocaust survivor Viktor Frankl drew evidence of meaning's therapeutic power from reflections garnered from his own internment,[18] and he created a variety of existential psychotherapy called logotherapy. In addition to May and Frankl, Swiss psychoanalyst Ludwig Binswanger and American psychologist George Kelly may be said to belong to the existential school.[19]


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In other views, organizational knowledge is not merely consider as individual one. Some of knowledge exist in group for [10]. Then the knowledge which is measured or measure something should cover 2 classification of knowledge i,e implicit and explicit and group, individual and organizational one.

The second dimension of this tetragonal basis of figure 1 is types of knowledge in an organization, individual and group from implicitly and explicitly.

 

 

 

 

 

Figure 2: equipoised cube for measurement method the necessities for

The cubical volume of figure 2 indicates integration of tetragonal base in measurement method with types of knowledge in organization

So we have a cube of 6 types of knowledge (from the intersection of implicit and explicit knowledge with indivisual, group, organizational knowledge) that each of then must be compared in the Tetragonal of "knowledge volume" , "knowledge volue" , "knowledge interest and expenses" and "Transformation speed of knowledge".

Now we should find a knowledge management model which is capable of integrating with this cognitive tetragonal model –Nonaka-

Jakichi Model is a suitable one to reconcile with this cognitive tetragonal model and can be considered as a basis for measurement model –Nonaka- Takochi Model as a cognitive model is based on types of knowledge. Hidden and obvious information have been discussed exactly in this model. In this model indivisual, group, organizational knowledge are converted to each other in a loop form too. [11] Then ,Nonaka. Takochi Model can be delineated as measurement Model base. But it should be mentioned here that this model has a dynamic nature.[12] in dynamic Models There are several main and important indexes that separate them from static ones.[13]

dependence to time; Dynamic models depend on time and in dingle of time they show different behavior from themselves which caused by main variable of time in them.

Cause and effect relationships: Dynamic Models are composed of varied cause and effect relationships. One cause itself can the effect of other cause. So in dynamic models the beginning strip of cause and effect relation ships is not clear but the cause and effect impacts of all indexes on each other is measurable and visible.

Feedback circles: in dynamic models feedback plays the main role. Any effect can effect on its cause. The increase of effect can boots or decrease cause directly or indirection.


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