In this paper, We prove that (1) a Tychonoff Space X is mesocompact if and only if every binary open cover of X×βX has a Compact - finite refinement by open rectangles, (2) A regular Space X is mesocompact if and only if every binary open cover of X× 2L(X) has a compact-finite refinement by open rectangles.

By this method, R-tree data organization was implemented by typical points approach in which spatial objects were replaced with their minimum boundary rectangles, and some performance targets such as covering, overlapping and boundary perimeter were modified to improve its query efficiency.

By leading the concept of parallelogrem with property E and the concept of square with property E ,the authors find out the number of parallelograms with property E (parallelogram E for short) and the number of square with property E (square E for short)from inclusive i×j rectangles in m×n rectangles;

A new algorithm which is used to transform center-hollowed polygons of CIF format in microlithography pattern into rectangles of PG3600 format is presented.

The two-dimensional identical rectangles packing problem is to pack the maximum number of identical small rectangles of size a × b (including b × a) into a large rectangle X × Y.

The 2(Object: one object vs.two objects)× 2(Location: short vs. long distance between two rectangles)× 3(Cueing: valid,inside-invalid or outside-invalid)within-subject experiment design was employed.

Defined a general Sierpinski carpet. Let S m be a general Sierpinski carpet with compression ratio 1/m(m≥4), S n be the set of n -th order elementary rectangle to produce S m,U be a subset in R 2 with diameter |U| >0, α n(U )denotes the number of the elementary rectangles intersecting Uin S n .

[6] regarding boundedness of maximal functions with respect to rectangles of lacunary directions, and prove a result regarding the cardinality of subsets of arithmetic progressions in sets of the type described above.

The necessary condition on the weight is similar to the Ap condition but involves rectangles (instead of cubes) arising from a covering of a star-shaped set related to Ω.

It has been proved that if a rectangle is dissected into three congruent pieces, then those pieces must themselves be rectangles.

Orthogonal packing of rectangles in a semi-infinite strip and its representation by block structures, which reduces the problem to a special linear cutting problem, are studied.

An exact solution is constructed to the problem of the stationary flow of an incompressible viscous fluid in a straight tube whose section is formed by two connected rectangles.

Occurrence of sporadic diseased plant centers during or after the bloomingperiod is considered as reliable indication of the current year's forthcomingoutbreak of late blight in a potato farm. Incubation period of each secondary infection being about 4 days,is ratherconstant during the blight epiphytotic season under Chahar conditions.The timeinterval between the appearance of initial diseased plant centers to final totalblight in a potato field varies greatly,however,not only from locality to localitywith different...

Occurrence of sporadic diseased plant centers during or after the bloomingperiod is considered as reliable indication of the current year's forthcomingoutbreak of late blight in a potato farm. Incubation period of each secondary infection being about 4 days,is ratherconstant during the blight epiphytotic season under Chahar conditions.The timeinterval between the appearance of initial diseased plant centers to final totalblight in a potato field varies greatly,however,not only from locality to localitywith different climatic conditions but also from field to field under similarclimatic conditions.Our data record a range of 18-42 days.Circumstantial eviden-ces indicate that this variation is due,on the one hand,to the rainfall whichinfluences the amounts of sporulation and the frequency of penetration of thepathogene,and on the other hand,to cultural and other factors that determinethe vigor and the rate of aging of the plant itself. Actual counts of lesions formed from secondary infection in the early periodof the spread of the disease in a potato field,reveal that their distribution bearsdirect relation with the direction of the prevailing wind.It is estimated that over90% of spores fall within a rectangle of 800 sq.m.around a diseased plantcenter along the loci of wind directions. On the basis of possible function of absorbed copper ions in the enhancementof plant resistance to late blight,field experiments have been conducted by using0.1 - 0.2% copper sulfate solutions as spray.Results show that spraying 2-3 timesat 7-10 days' interval,started soon after the appearance of diseased plant center,gives remarkable control of late blight and corresponding reduction of loss inyield.The copper sulfate spray,though less effective and stable in comparisonwith the bordeaux spray,has the advantage of being more economical and easierto apply.Further experiments with the pu:pose of modifying and improving themethod are in progress.

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.