نشریه اطلاعات جغرافیایی (سپهر)
پیاپی 40 (زمستان 1380)

The images are formed through the change in the strength of brightness of the scene upon the film. At first glance, in aerial photography such changes are related only to the change in the type of the land feature. Of course, this hypothesis is an over-simplification of the issue, because there are many factors that are not related to the type or conditions of a land feature and can affect the measurements of the exposure value of the film. Since the above-mentioned factors affect the measurement of exposure but do not play a role in the true changes of the type of land cover due to conditions, they are called "external effects". Here, the major geometric effects that affect the exposure of the film are discussed.
 

Generally speaking, one of the definitions presented for maps is: drawing images of a part or whole of the surface of the earth at a given scale on a flat and horizontal plane. On the other hand, geomorphology is a science that is related to the study of landforms or forms of terrains especially in terms of their origin and the various processes that create them. Geomorphology studies, based on their nature, are in four topics of studying the materials on which landforms are taken shape, studying the processes that shape the material, and studying the evolution and history of landscapes. Thus, the purpose of geomorphologic mapping is to record information about the surface shape, material (soil and stone), surface processes and, in some cases, age of terrains. The maps thus prepared contain basic information on land systems and can be used in most environmental issues such as land use studies, natural resources and agriculture, surface and underground water, civil engineering, exploration and extraction of mineral resources and so on.

Military geography is a science which is considered as one of the branches of geography according to one of the comprehensive definitions of this science. It examines the impact of natural and cultural environment on military / political attitudes, plans and all types of combat and support operations on the world, regional and local scales. Spatial relationships are undoubtedly among the most important geographic elements and factors. The position, size and shape of land, along with the location of the water that is on the military activities' path, form the basis on which all land features are positioned. Dry lands of the earth include three major parts that are militarily important, namely the highest, the widest, and the deepest lands, each of which has its own unique conditions and includes distinctions and special methods.

Each numerical or geometric quantity, or sets of numerical quantities, which are used as reference or basis for other quantities, are called base levels or datums. In geomorphology, two different baseline levels are considered, one of which is flat, which forms the basis of the accurate calculation in horizontal surveying in which the curvature of the earth's surface is considered. The other is the elevation base level according to which the height of points are measured and calculated. In other words, in geodetic surveying the coordinates of different points are obtained from a series of initial points with known coordinates by base line parameters. Due to the development of different methods in surveying, several datums or baselines have been defined and produced. Today, several datum have been defined and produced for development of geodetic surveying and satellite geodetic methods, and there is no need to have more than one datum in this method. But this does not mean a complete replacement of all datums by a single one, since in practice there are initial surveying parameters and quantities that each depend on the different datums. On the other hand, the overall change of datums will require a century to transform all the information in the maps of a country into a new base level. For example, the issue of determining the sovereignty over the border lines of the US state has been on since centuries ago, and even by drawing up a map of disputed borders, military and civilian users still prefer the old systems of surveying measurement over new ones due to special reasons. Consequently, making general changes in determining the base level not only does not eliminate the problem, but may add another variable to initial problems.

In this article, Robert Barre, while outlining the consequences of the abandonment of Mr. Robinson from the Ordnance Survey of England, states that this would create a war on geographic information in the future.

Forestry management considers forests for wood, forage, water, wildlife and recreation. Since the main and raw product of forest is wood, forestry especially considers management of lands that contain logging trees, restoration and improvement of forest condition and fire control. Approximately a third of the earth is covered by various forest types. They have been irregularly distributed and their capital values change regularly. Interpretation of aerial photographs provides an easy way to check their condition.

In the round sky where the stars stand firm, astronomers noticed seven wandering objects that were moving eastward in the sky. They include the Sun, the Moon, Mercury, Venus, Mars, Jupiter and Saturn. Each of these wandering objects is associated with one of the days of the week, so in modern English, the link between this list and the names of weekdays is revealed in Sunday, Monday, Saturday, but in other languages other criteria have been used for naming weekdays.

Study on rural industries is undoubtedly one of the most important economic necessities, because population growth and consequently the reduction of facilities cause unemployment unless some of these deficiencies and problems are reduced and diminished. Therefore, industrialization of villages in its real sense is one of the important functions in terms of employment, raising the income of individuals and ultimately preventing migrations from villages to cities, because the villagers' departure from villages will not only not solve the problem of villages but indeed intensify them. Considering that rural industries are complementary to the agricultural and animal husbandry sectors, we intend to examine this issue and, in general, define rural industries and their characteristics, classify them and study the importance of development and support methods, the problems of establishing these industries, the difference between urban and rural industries and the position of these industries in Iran's economy. It is hoped that this effort will show a way forward for the future and the authorities to stop the continuous rural migrations by developing rural industries and creating employment.

Considering the importance of workshop equipment in massive civilian operations, it should be acknowledged that the equipment of a construction workshop is not comparable to that of other workshops. Hence, a number of points are noted in this regard as follows: - Estimation of workshop equipment costs should be carried out by the consultant engineering firm in proportion to the total project. Consultant will make the necessary predictions in specifications or price list on how to pay for workshop equipment costs in accordance with relevant instructions and considering the schedule of the implementation of workshop equipment. The percentage of the cost of workshop equipment is not constant and varies according to the type of the project and its characteristics, as well as topographic and climatic conditions of the plan’s site. - The purpose of equipping and dismantling workshops is to supply buildings, facilities, equipment and machinery through constructing, installing or controlling them based on facilities on site and in the form of purchase or leasing of services.

Our present knowledge regarding artificial increase of precipitation has a definition as follows: application of appropriate fertility materials at the right time and place that makes changes in clouds, so that clouds behave in a different and predictable way and satisfying results are achieved. The technology of cloud fertilization is developed with the aim of providing the means and facilities for achieving this kind of interference in cloud processes and thus uses scientific considerations in its implementation. According to our knowledge, nature produces rain in very diverse cloud conditions through two different major processes, and if we seek useful results, the technology mentioned above should be applied with the exact knowledge of real and natural processes. On the other hand, the current state of the physics of clouds is such that at best it can provide guidelines, rather than detailed instructions, for implementation of technology in accordance with different cloud conditions. Compared to some of the existing approaches to cloud modification, which require "engineering", this scientific effort is the main branch of ongoing research activities. It is better to admit that the principles of technology discussed in the following have relatively limited scientific bases, and their implementation is only carried out in the light of a clear understanding of the ambiguities that still need to be explained. Cloud fertilization technology includes two important components: 1- Application of suitable fertility strategies. 2- Fertilizing materials’ production technology.

Women comprise almost half of the rural population, and more than half of rural socio-economic activities rely on their efforts, but before 1970 it was assumed that the process of development affected men and women equally, because at the time the amount of production was in balance with the cash economy; consequently much of the work by women was ignored. When it became clear that economic development does not automatically eradicate poverty through the effects of "penetrating down", the issue of equal distribution of benefits between men and women has become of major importance in developmental theories, and the topic of human force development and related issues have been raised. The members of rural communities in general and rural women in particular are undiscovered treasures that have always suffered cultural deprivation due to lack of access to cultural resources and in particular the educational facilities. As a result, they have never been able to fully utilize their innate abilities and talents and have always faced inattention by the authorities and others in the process of development. A look at the situation of rural women in Iran and the extent of participation of women in developmental planning will make this matter clearer.

Evaporation is the process of change of water into steam in which water molecules leave the surface of water by receiving 600 Calories. This process can be carried out either from the surface of open water or soil or by plants. The amount of water that plants release into the atmosphere is called transpiration. The amount of evaporation from soil and plant surfaces cannot be separated, so the sum of the two is called evapotranspiration. The significance of evapotranspiration can be witnessed by considering the fact that 57% of the water which falls on lands all over the world is directly evaporated. The factors affecting evaporation are many, including: solar radiation, moisture content in nature, wind and its speed. The sun's radiation provides the energy needed for evaporation; hence during the day and in the summer there is more energy for evaporation due to more radiation, and evaporation is at its peak at this time. The same is true about northern latitudes. The humidity or degree of air saturation is also effective in evaporation, as evaporation in dry air is more than humid air; furthermore, wind intensifies evaporation by removing the saturation layer and replacing dry air. Measurement of evapotranspiration in different regions is important in several respects: First, it controls the humidity of the region through evaporation, and therefore its measurement can be effective in determining the type of the region’s climate. Secondly, evaporation from the surface of rivers, lakes and various reservoirs causes water losses that need to be calculated. Thirdly, evapotranspiration from the vegetation within the basin area, which is also considered as water loss, is regarded as an important component of water cycle. Fourthly, the amount of water used in irrigation schemes for agriculture and trees is also based on evapotranspiration, and determination of dimensions of irrigation networks is directly related to the amount and time of the loss of water entered into atmosphere through evapotranspiration. Since the province of Hamedan is considered as one of the agricultural regions of the country, it is necessary to study evapotranspiration and its amount in this province in order to estimate the actual needs of plant to water and also further the economic development of the region. Measurement of evapotranspiration is carried out in two ways: the direct method, which is measured by the lysimeter and evaporation pan, etc., and the second method, which is an experimental measurement in which practical formulas and equations are used to estimate the evapotranspiration rate.