By applying right (left) greatest common divisor in row (column) simplest form, the representation of the set constructed by all right (left) greatest divisors of A and B can be given, and the simple method for solving them can also be given.

Next,the concept of graded semiflat module is introduced and proved that K is a group-graded weakly regular ring if and only if all right K-module is graded semiflat module.

2. The analysis of positive relationships among some elements in surficial sediments indicate that the elements between Cr and Ni, Ni and Hg, Zn and Cd have good correlation, the coefficient are 0.97~ 0.99; the correlation is all right between the elements of Cr with Hg, Pb, As , Ni with As, Pb, Pb with Hg, the coefficient are 0.82~0.89, which show this elements have the same source of geochemistry and man-made pollution.

Studies were performed on 33 students (all right-handed) aged 18-28 years.

The product of spaces Φ × D is considered, where Φ is the set of all continuous, nondecreasing functions ?:[0,∞)→(0,∞), ?(0)=0, ?(t)→∞(t→∞), and D is the set of all right continuous functions ξ:(0,∞)→X; here X is some metric space.

Twenty-eight mother-infant pairs (14 left-handed and 14 right-handed infants but all right-handed mothers) were videotaped while playing with six toys on the infant's 7-, 9-, and 11-month birthdays.

The idea is to collect (bunch) all right-hand sides that have the same optimal basis, and to organize the search for these bases efficiently.

Archeops is designed to observe a complete annulus on the sky covering all right ascensions between about 25 and 55 degrees during the course of a 24-hour Arctic-night balloon flight, in four frequency bands centered at 143, 217, 353 and 545 GHz.

1、The constitution of the quick-growing and good harvest forest of Populus canadensis consists of the form of planting composition and planting distance. It de- termines the nursing and leaves' space, large or small, of forest tree, hence it in- fluences the amount of out-pat aud quality of timbers. There are differeut opinions to the proper constitution. To study it is very important. 2、In foreign countries the constitution of poplar forest is quite different. The form of planting is sometimes square or rectangle....

1、The constitution of the quick-growing and good harvest forest of Populus canadensis consists of the form of planting composition and planting distance. It de- termines the nursing and leaves' space, large or small, of forest tree, hence it in- fluences the amount of out-pat aud quality of timbers. There are differeut opinions to the proper constitution. To study it is very important. 2、In foreign countries the constitution of poplar forest is quite different. The form of planting is sometimes square or rectangle. Some countries adopt close plant- ing, and others adopt open. In general, square and rectangle are adopted in artificial forest of Populus canadensis, while triangle planting is rearly used. A tendeucy is to use close planting. There are 400 to 40,000 planting thocks in per hectare. The difference is 100--times. 3、The rational close planting of Populus canadensis is right triangle aud square, because in such condition the orown may be normally developed, and striaght bole maintained. In the oircumstances of the same planting distance, the right triangle planting site produces 15.5% more products than thesquare (planting). Populus canadesis is a very intolerant species with high adaptability and de- mands water more than fertilizer. As the climatical and soil conditions are favourable, especially water is available and guaranteed, the density of planting may be deter- mined according to the following factors: (1) In eccordance with the table of the average height and diameter of tree in relating to the planting distance, at the first intermittent cutting, to resolve the planting distance: As the average height and diameter of the tree is known, at the first intermittent cutting, the corresponding rational distance of the first planting will be then easy found out from the table. on the other hand, the square value of the normal growing crown is used as a standard to determine the nursing spare and planting distance. In the mean time the first intermittent cutting year may be ob- tained. (2) To find out the rational close of planting by means of the soil fertility and the intensity of managenient: When the condition of soil fertility and water is suitable and the intensity of management is high, the trees grow fast the crown clo- sure is quick, open stocked in first planting is all right, dsing 3.5 × 4--6 × 6 M. in distance. If the condition of site is not good the site should be planted first close then open, using 1.3 × 1 .5--3 × 3 M. in distance promoting the crown in early closure, then thinning and transplanting the seedlings to the open site or plan- ting shrubs or farm crops between the rows of planting. (3) To find out the rational close of planting by means of the year and stan- dard of planting stocks: At the same conditions of site and management, one year seedlings or slips are used in close planting. While 2--3 year seedlings, 3--4 meters in height, are used in open planting. First close planting then open, as the plant- ing stocks grow 1--2 years 1ater, the dense stocked seedlings should be thinned and transplanted in the near by planting area. Then both sites become open stocked forests.

1、The constitution of the quick-growing and good zharvest forest of Populus canadensis consists of the form of planting composition and planting distance.It de- termines the nursing and leaves'space,large or small,of forest tree,hence it in- fluences the amount of out-put and quality of timbers.There are different opinions to the proper constitution.To study it is very important. 2、In foreign countries the constitution of poplar forest is quite different.The form of planting is sometimes square or rectangle.Some...

1、The constitution of the quick-growing and good zharvest forest of Populus canadensis consists of the form of planting composition and planting distance.It de- termines the nursing and leaves'space,large or small,of forest tree,hence it in- fluences the amount of out-put and quality of timbers.There are different opinions to the proper constitution.To study it is very important. 2、In foreign countries the constitution of poplar forest is quite different.The form of planting is sometimes square or rectangle.Some countries adopt close plant- ing,and others adopt open.In general,square and rectangle are adopted in artifioial forest of Populus canadensis,while triangle planting is rearly used.A tendency is to use close planting.There are 400 to 40,000 planting stocks in per hectare.The difference is 100-times. 3、The rational close planting of Populus canadensis is right triangle and square, because in such condition the crown may be normally developed,and striaght bole maintained.In the circumstances of the same planting distance,the right triangle planting site produces 15.5% more products than thesquare (planting). Populus canadesis is a very intolerant species with high adaptability and de- mands water more than fertilizer.As the climatical and soil conditions are favourable, especially water is available and guaranteed,the density of planting may be deter- mined according to the following factors: (1)In accordance with the table of the average height and diameter of tree in relating to the planting distance,at the first intermittent cutting,to resolve the planting distance:As the average height and diameter of the tree is known,at the first intermittent cutting,the corresponding rational distance of the first planting will be then easy found out from the table,on the other hand,the square value of the normal growing crown is used as a standard to determine the nursing space and planting distance.In the mean time the first intermittent cutting year may be ob- tained. (2)To find out the rational Close of planting by means of the soil fertility and the intensity of management:When the condition of soil fertility and water is Suitable and the intensity of management is high,the trees grow fast the crown clo- sure is quick,open stocked in first planting is all right,using 3.5×4-6×6M. in distance.If the condition of site is not good the site should be planted first close then open,using 1.3×1.5-3×3M.in distance promoting the crown in early closure,then thinning and transplanting the seedlings to the open site or plan- ting shrubs or farm crops between the rows of planting. (3)To find out the rational close of planting by meaus of the year and stam- dard of planting stocks:At the same conditions of site and management,one year seedlings or slips are used in close planting.While 2-3 year seedlings,3-4 meters in height,are used in open planting.First close planting then open,as the plant- ing stOcks grow 1-2 years later,the dense stocked seedlings should be thinned and transplanted in the near by planting area.Then both sites become open stocked forests.

To determine an investment scheme that allows the limited capital to grow with the maximun economical profit,is an important problem in decisive pro- cess.The nature of such Problems belongs to combinatorial optimization.Algorithm to get optimum solutions of combinatorial problems may be tedious.Some times,the optimum algorithms take such a long lime that they cannot be used in practice.Thus, heuristics are preferred,which intuitively seems to be all right and sometimes do obtain optimum solution.This...

To determine an investment scheme that allows the limited capital to grow with the maximun economical profit,is an important problem in decisive pro- cess.The nature of such Problems belongs to combinatorial optimization.Algorithm to get optimum solutions of combinatorial problems may be tedious.Some times,the optimum algorithms take such a long lime that they cannot be used in practice.Thus, heuristics are preferred,which intuitively seems to be all right and sometimes do obtain optimum solution.This paper presents two optimizing methods to obtain a near- optimum solution. 1.Dynamic programming associated with network theory. 2.Branch and bound method in form of a decision tree.