Symmetries in images on ancient seals--论文代写范文精选

第一种可能性是遵循美学意义上,其中包括观察的乐趣和平衡形式。与人类感知紧密相连。对称的第二个意义是良好的自相似性,这可以根据精确的操作，这是科学的对称。下面的paper代写范文进行论述。

Abstract 
In this paper, we discuss the presence of symmetries in images engraved on ancient seals, in particular on stamp seals. Mainly used to secure the containers from tampering and for owner's identification, these objects appeared during the 5th millennium BC in Mesopotamia. Usually the seals were engraved with simple images, suitable to communicate immediate information. Rotational symmetries are already displayed by the most ancient stamp seals, whose images reach a quasi-perfect symmetry in their small circular or ovoid spaces. Bilateral symmetries are quite common in Egyptian scarab seals.

Introduction
If we want to discuss about symmetry, we have two possibilities. The first possibility is to follow the aesthetic sense, which involves the pleasure in observing good proportioned and balanced forms. The simplest symmetry, the bilateral one, seems to be deeply connected with human perception, as a character of health and then beauty of living beings. The second meaning of symmetry is a well-defined concept of pattern self-similarity, which can be proved according to precise operations in time and space. This is the symmetry in science. In physics for instance, symmetry means invariance of the physical laws under specific transformations. Conservation of energy, momentum and angular momentum can be viewed as a consequence of symmetry for continuous translation in time and space and for rotation. 

The use of symmetry in science is not separated from a certain aesthetics satisfaction that we gain with these theoretical descriptions [1]. An innate inclination to view symmetrical objects as beautiful produces a consequent improvement of the visual result of many human artefacts. In this paper, we will discuss the presence of symmetry in some ancient artefacts, the stamp seals. They were objects widely used, mainly for sealing and identification purposes, at any social level. Usually engraved with very simple images, they were suitable to communicate immediate information to people. Considered as a form of art of non-primary importance, engraved images can be not only beautiful but also rather important for archaeological studies. We will see that, sometimes, the images reach a quasi-perfect symmetry in their small circular or ovoid spaces. Before the discussion on symmetry, let us shortly report information on the time-line development of seals.

The ancient seals 
Sealing is the impression made by the impact of a hard-engraved surface on a softer material, such as clay or wax. The word seal (Latin “sigillum”, old French “scel”) refers either to the device or to the impression. Ancient stamp seals and cylinder seals were made of a hard material, usually stone, and used to press an engraved figure or a short inscription into soft clay. In ancient times, seals were used for the securing of bags, baskets, jars, etc.. The sealing method was either to shape clay over the container stopper or make a fastening with cord and place clay around the knot. The impressed seals on clay were both used to avoid tampering and as method of identification of content or owner.

The seals were of two main types, the cylinder and the stamp. The cylinder first appeared in Mesopotamia in the late 4th millennium BC, then widespread in Syria and Egypt and in the Aegean area. Stamp seals preceded cylinders, first appearing in Mesopotamia in the 5th millennium BC. Early stamp seals were also used in Iran, northern Syria, and Anatolia (4th and 3rd millennia BC). In Egypt, the scarab seals largely replaced cylinder seals early in the 2nd millennium BC and continued as the main type. They were replaced by the signet ring in Roman period. In the Aegean, stamp seals were used throughout the 2nd and much of the 1st millennium BC, until the signet ring became dominant, in Hellenistic and Roman times [2]. For Egyptians, the scarab seal was not only an impression seal: it was also an amulet with images and symbols engraved to protect the owner [3]. 

Scarabs were used extensively in Egypt, but they became quite popular and produced also outside of Egypt. In fact, stamp seals with round or ovoid shapes are considered as scarab seals, even when the round back of the object is not precisely shaped as a scarab. Images on seals are of several types. In the case of Egyptian scarabs, we find of course inscriptions with names of kings and gods, human figures and animals. Coils and entanglements of cords are characteristic of the Middle Kingdom Period. Among images of animals, goats and antelopes had a great success during the Hyksos period, because Hyksos took the antelope form of the Egyptian god Seth to represent their own deity [3]. In the case of Egyptian scarabs, books reporting the collections are available on public domain [4-6]. It is therefore possible to create a sort of statistics of the used images and check if symmetries are present and what are the preferred image arrangements. We find a relevant number of stamp seals with cords and coils, highly symmetric, mainly with bilateral symmetry (see Fig.1), sometimes with two- and four-fold rotational symmetry.

The mirror symmetry, or bilateral symmetry, is the symmetry with respect to reflection. A figure, which is indistinguishable from its mirror image, is called mirror symmetric. A way to think about this symmetry is to fold the image in the middle, and check if the two halves are identical. In this case, the image has two halves that are each other's mirror image. Rotational symmetry is symmetry with respect to rotations in the space. In the case of an image, it has a rotational symmetry, when we observe that it is invariant for rotation about an axis perpendicular to its plane. We find a two-fold symmetry if we rotate the image of 180 degrees, a four-fold one when the rotation is of 90 degrees. Generally, we have n-fold rotation when angle is 2π/n.(paper代写)

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