DRESSING OF CORUNDUM WHEEL WITH POLY CRYSTALLINE DIAMOND

Wheel dressing is an important part of grinding, it influences not only the grinding quality ofthe workpiece,but also the cost of grinding.At present the single point mined diamond is widelyused as dresser in industry.Because the mined diamond is rare in nature and dear,it has a practicalsignificance to find a substituting material for the mined diamond.Due to the isotropy of PCD(polyerystalline diamond),new sharp cutting edges will expose continuously during dressing opera-tions,maintaining high dressing efficiency.Tests show that dressing corundum wheel,especiallydressing those for internal grinding,PCD dresser is suitable to common hardnesses,and grains ofwheels and smaller depth of dressing.The authors consider that PCD dressing can be used to sub-stitute completely the mined diamond dresser and the cost of dressing may be reduced.     

ESTIMATION OF BLENDING RATIO OF TWO-COMPONENT FIBER BUNDLE FROM BUNDLE LOAD-ELONGATION CURVE

In this paper, two methods were developed to assess the blending ratio of two-componentfiber bundles. They were the peak-height method and the slope method. The relationship be-tween blending ratio and testing data was analysed, and the regression curves were obtained bystepwise regression method. It was pointed out that the testing errors of both methods were lessthan two percent. The validities of both methods were verified by experiments, All calculationsof both methods were completed by computer. The blending ratio was ascertained from the test-ing data of bundle fiber strength tester which was made by the authors themselves.     

ON THE DISCRETE APPROXIMATE SOLUTION AND ESTIMATION OF ITS ERROR OF THE NONLINEAR SINGULAR INTGRAL EQUATIONS

With the help of discrete singular operator S this paper deals with the discretization of the equationsWe divide interval [a , b] into 2N parts: [t_i, t_(i+1)], with i=1 ,2 ,… ,2N, where t_1 =a, t_(2N+1)=b,t_(i+1)-t_i=(b-a)/2N=h_N, i=1,2,…,2N.From [1], linear operator S(N): E_(2N-3)→E_(2v-3), for all Z=(z_3,z_4…,z_(2N-1))∈E_(2n-3),S~(N)Z=(S_2~(N)Z,S_4~(N)Z,…,S_((2N-1)~(N)) Z), there will be     

A STUDY OF THE MORPHOLOGY OF POLY(1,4 PHENYLEN TEREPHATHALAMIDE) (PPTA) PULP

The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, which are very important for PPTA pulp as a reinforcer. Theseparation limitation of PPTA pulp is also investigated from both torn and brittle break cross-sec-tion. A packing mechanism is proposed to illustrate the microfibril packing in the gel system.     

PREPARATION AND MECHANICAL PROPERTIES OF POLY(METHYL METHACRYLATE)/ URETHANE ACRYLATE COPOLYMERS

The urethane acrylate(UA) was made of poly(tetramethylenc oxide), 4,4'-diphenylmethane diisocyanate, and 2-hydroxyethyl methacrylate. A series of poly(methyl methacrylate) / urethane acrylate copolymers was prepared by using a redox initiating system. The copolymers had cross linked structures and two-phase morphologies as indicated by the results of the dynamic mechanical measurement and swelling test.     

SYNTHESIS AND PROPERTIES OF POLYURETHANE MODIFIED WITH AMINOETHYLAMINOPROPYL POLY(DIMETHYL SILOXANE)

Ｍｕｌｔｉｐｈａｓｅｓｅｇｍｅｎｔｅｄｓｉｌｏｘａｎｅｕｒｅｔｈａｎｅｃｏｐｏｌｙｍｅｒｓｈａｖｅｂｅｅｎｒｅｐｏｒｔｅｄｉｎｔｈｅｌｉｔｅｒａｔｕｒｅｗｈｉｃｈｗｅｒｅｐｒｅｐａｒｅｄｂｙｐｒｉｍａｒｙｏｒｓｅｃｏｎｄａｒｙａｍｉｎｅｔｅｒｍｉｎａｔｅｄｓｉｌｏｘａｎｅｏｌｉｇｏｍｅｒｓｗｉｔｈｄｉｉｓｏｃｙａｎａｔｅｓａｎｄｄｉｏｌｓ［１～６］．Ｈｏｗｅｖｅｒ，ｂｅｃａｕｓｅｏｆｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆＰＤＭＳｉｎｔｏｔｈｅｍａｉｎｃｈａｉｎｏｆｐｏｌｙｕｒｅｔｈａｎｅ，ｔｈ…     

THE STRUCTURE AND PROPERTIES OF FINE DENIER HOLLOW POLY(ETHYLENE TEREPHTALATE) FIBRES

Using brighten white and modified PET chips, fine denier hollow fibres (dpf=0.5～1.5) were prepared on a Fuji Filter MSTC-400 and VC-443A drawn machine, whose structure and properties were tested by X-ray diffraction mater, SOM-II sonic velocity meter and Instron-1122 Tensile tester, electron and light microscopy etc,. The results show: fine denier hollow taken-up yarns prepared at low spinning velocity have radial orientation, higher strength and elongation at rupture because radial stress is higher than normal stress. Fine denier hollow drawn yarns with hollow degree up to 18～35％ and high tenacity, together with high crystalline degree and small crystal and amorphous domains, can be empolyed as products.     

PREPARATION AND CHARACTERIZATION OF ULTRA-HIGH MOLECULAR WEIGHT POLY(ETHYLENE TEREPHTHALATE)(PET)FIBER

This paper reports the spinning and drawing behavior of Ultra-high Molecular Weight polyethylene Terephthalate) (UHMW-PET) fibers. The as-spun fibers were produced by dry-jet wet spinning of a 15%-17% solution in 50:50(v:v) trifluroroacetic acid and dichloromethane. Both molecular weight and polymer solution concentration have marked effect on the drawability of the as-spun-fibers. The maximum extension drawing ratio (EDRmax) of as-spun fiber increases with increasing molecular weight, whereas optimal concentration to achieve the EDRmax of as-spun fibers decreases with increasing molecular weight. Drawing speed and temperature during the first step have remarkable effect on the drawability of these fiber during the second step. Relatively lower drawing temperature and drawing speed (19 ℃ , 60 mm/min) during the first drawing step was beneficial to mechanical properties of ultimate fibers. At the range of 210 ℃ to 230 ℃, the draw ratio (DR) during the second step increases with increasing temperature.     

THE OPTICAL OBSERVATION OF THE COLLISTIONS OF COMET SHOEMAKER－LEVY 9 WITH JUPITER

ＴＨＥＯＰＴＩＣＡＬＯＢＳＥＲＶＡＴＩＯＮＯＦＴＨＥＣＯＬＬＩＳＴＩＯＮＳＯＦＣＯＭＥＴＳＨＯＥＭＡＫＥＲ－ＬＥＶＹ９ＷＩＴＨＪＵＰＩＴＥＲ￥ＺｈｏｕＨｏｎｇｎａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＡｓｔｒｏｎｏｍｙ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，２１...     

CELL——未来电动车

<正>"CELL"为我们描述了一种未来交通系统的新概念:驾驶者并不是拥有某一特定的车,他们只是拥有一个共享系统,可以选择车辆送他们到目的地。这种载两人,可变形的电动车由设计师汤姆·凯特设计,它能够降     

THE EFFECT OF ZnO ON BURNING OF PORTLAND CEMENT CLLNKER IN RAPID MEATING－UP BURNING

ＴＨＥＥＦＦＥＣＴＯＦＺｎＯＯＮＢＵＲＮＩＮＧＯＦＰＯＲＴＬＡＮＤＣＥＭＥＮＴＣＬＬＮＫＥＲＩＮＲＡＰＩＤＨＥＡＴＩＮＧ－ＵＰＢＵＲＮＩＮＧＸｕＧｕａｎｇｌｉａｎｇＳｏｕｔｈｗｅｓｔＩＮｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙＨｕａｎｇＷｅｎｘｉＣｈｅ...     

CLINICAL USE OF HEAMONETICS TYPES V50BOD LO CELL SEPARATOL AND ITS INFLUENCE ON THE HUMAN BODY

Published in J. of Haematology.1985; 6/9:532-533. Hemonetics Type v50 blood cell separator has been used by us to perform simple collectetion of blood elememts and plasma exchange to ensure the special need for blood clinically. Such as infection or bleeding due to agranulocytop-enia or thrombocytopenia from various clinical causes which repoads satisfactority to elememt blood transfusion.     

THE COMPARISON OF STRENGTH PROPERTY BETWWEEN KRAFT PULP AND ALKALINE SULFITE-ANTHRAQUINONE PULP FOR THICKER CELL WALL FIBER MATERIALS

INTRODUCTIONMany studies on the strengths of AS-AQ pulp have been carried out. Generally speaking, except lower tear strength, other strength properties of AS-AQ pulp are similar to those of KP. Some even higher than KP[1,2]. Macleod[3] find that the difference in tear strength between the AS-AQ pulp and KP of aspen can be decreased about bleaching. McDonough et al[4] point out that at the same beating degree, the tear strength of AS-AQ pulp is lower than that of KP, but at the …     

DISCOVERY OF MICROFOSSILS FROM THE 1848－MA－OLD CHANGZHOUGOU FORMATION，JIXIAN SECTION，NORTH CHINA

ＤＩＳＣＯＶＥＲＹＯＦＭＩＣＲＯＦＯＳＳＩＬＳＦＲＯＭＴＨＥ１８４８－ＭＡ－ＯＬＤＣＨＡＮＧＺＨＯＵＧＯＵＦＯＲＭＡＴＩＯＮ，ＪＩＸＩＡＮＳＥＣＴＩＯＮ，ＮＯＲＴＨＣＨＩＮＡＺｈａｎｇＺｈｏｎｇｙｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＥａｒｔｈＳｃｉｅｎｃ...