COMPARATIVE TESTS OF ENGLISH AND DOMESTIC WHITINGS1

A knowledge of the properties of American whiting as compared with those imported from England is of importance to producers of the American material as well as to manufacturers of products in which whiting may be used. Twenty-two samples of domestic and foreign whiting have been submitted to examination and tested as follows: (1) visual examination, (2) microscopic examination, (3) determination of fineness of grain by three methods, (4) partial chemical analysis, (5) effect of the different whitings on the softening point of ceramic cone mixtures, and (6) effect on rate of vitrification of porcelain bodies. The results indicate that although the English whitings contain considerably more fine material of a colloidal nature, the American whitings appear to be sufficiently fine grained for all ceramic purposes. This extreme fineness may play a part in assisting in the flotation of the frit in glazes containing a low percentage of clay, but apparently has no effect in the fluxing point of ceramic glaze or body mixtures. Sufficient data has been obtained to permit of the preparation of tentative specifications for whiting for ceramic purposes and the main requirements of such a material are given.     

统计学方法在玻璃钢力学性能测试能力比对检验中的应用

本文叙述了统计学方法在玻璃钢力学性能测试能力比对检验中的应用,通过3个示例以t-检验对结果的一致性进行了肯定或否定的判断.     

COMPARATIVE TESTS OF AMERICAN AND FOREIGN TABLE WARE1

The absorptions, porosities, and bulk specific gravities are given. It was found that the American wares were superior to the English, French, German, and Japanese wares tested in resistance to either crazing or sudden temperature changes. The American hotel wares withstood much greater impact than the imported hotel wares, and the domestic earthenware and china for household use was superior to the foreign chinas tested, which were brittle. The resistance of hotel wares to chipping at the edge appeared to depend more on the design of the edge and the angle of inclination of the rim, than on the inherent properties of the bodies. All of the glazes were found to be unaffected by boiling in alkaline solutions for a period of twenty-five hours.     

COMPARATIVE TESTS OF SOME AMERICAN AND GERMAN FIRECLAY BRICK1

The Bureau of Standards has recently completed a short investigation comprising comparative tests of five brands of German-made brick and six brands of American-made brick. The results indicate that the Ge man-made brick are practically the equal of the American brick.     

COMPARATIVE SERVICE TESTS OF GROSS ALMERODE AND DOMESTIC CLAY POTS1

Glass-drawing pots made from Gross Almerode clay proved to be superior in a service test to pots made from a synthetic siliceous domestic clay mixture. When removed from service the faces of the Gross Almerode pots are pitted. The faces of domestic clay pots are surface cracked. The blistering of the glass caused by this cracking is eliminated by substituting silica brick grog for fire clay grog.     

COMPARATIVE TESTS ON MONOLITHIC REFRACTORY CEMENTS1

Samples of the leading monolithic cements on the market were subjected to laboratory tests. The three best cements as determined by the laboratory tests were then subjected to various tests under practical working conditions. This paper covers all the laboratory and practical working tests up to date.     

REACTIONS OCCURRING IN DECORATION OF VITRIFIED CHINAWARE USING UNDERGLAZE DECALCOMANIA METHOD*

Studies were made on the causes of defects in underglaze decalcomania transfer on vitreous hotel chinaware. The best hardening-on firing schedule to eliminate frizzling was as follows: (1) Heat as rapidly as ware will permit to 600°F., (2) at 600° to 800°F., heat at rate not exceeding 40° to 50°F. per hour, and (3) above 800 °F., heat as rapidly as ware will permit. The hardening-on fire can be eliminated by reducing the coating of varnish through control of the viscosity of the varnish in the range of 4.0 to 6.0 (Mac-Michael viscosimeter with No. 30 B & S wire, with cup rotating at 19 r.p.m.). The best results on the tackiness period were obtained in a room at 74 °F. dry bulb and 73% relative humidity.     

COMPARATIVE TESTS OF POROSITY AND SPECIFIC GRAVITY ON DIFFERENT TYPES OF REFRACTORY BRICK1

Comparative data of porosity and specific gravity on several types of refractory brick are presented. Apparent porosity is obtained directly by the water absorption and air expansion methods. Total porosity is calculated from the true specific gravity and apparent specific gravity is calculated from the observed porosity values. The results indicate (1) a more accurate measurement of open pore space in bricks by means of the air expansion method than by water absorption, and (2) the absence of sealed pores in some types of refractory brick.     

USE OF THE SIMULATIVE TEST FURNACE AS A MEANS OF MAKING COMPARATIVE TESTS OF FIRE BRICK1

The Navy Simulative Service Test for refractories is described, specifications for the test and the furnace used being given. The simulative service furnace has found application in making comparative tests of different brands of refractories, development of and improvement of standard fire brick, and as a control test for maintaining quality of the product.     

COMPARATIVE POWER STUDIES FOR GOODNESS OF FIT TESTS OF TIME SERIES MODELS

Abstract. Power studies for three tests of fit, namely the classical test given by Whittle, the widely-known test given by Ljung and Box, and the recent test given by Godolphin, are derived for the invertible time series models considered previously in an empirical study. The results demonstrate that it is possible to improve on the Ljung-Box test by employing more empirically-based alternatives. In particular, the test derived by Godolphin appears to be more powerful than the other tests. The results also suggest that the Whittle and Ljung-Box tests are complementary, so that the combination of both may yield a sensitive test procedure.     

碳纤维增强树脂基复合材料孔隙率检测方法的分析比较

碳纤维增强树脂基复合材料生产过程中会产生孔隙的缺陷,孔隙会对性能造成影响,故需要对孔隙含量进行标定。以碳纤维增强双马酰亚胺树脂为研究对象,分别采用密度法、显微照相法、超声检测法、高精度X射线数字成像法等4种方法,对热压罐和微波固化成型法制备的层压板孔隙缺陷进行检测,并计算其孔隙率。研究结果表明,显微照相法、高精度X射线数字成像技术法测试的孔隙率接近,密度法的误差较大。     

WASHING TESTS OF GEORGIA CLAYS1

The Whirlpool Classifier .—A device is described by which the impurity in a clay can be separated more efficiently than is possible by simple elutriation processes. Washing Plants .—A semi-commercial plant used to wash 1000-lb. samples is described, together with a suggested plan for a commercial plant. Beneficiation of Georgia Clays .—Results obtained on several Georgia sedimentary clays are given. The washed clays are reported free from grit and material producing specks in burned ware as well as improved in color, both in the raw and burned state.     

双相成核剂制备牙用烤瓷粉的研究

在SiO2-Al2O3-K2O-Na2O体系的基质玻璃中引入双相成核剂CaF2和TiO2来制备牙用烤瓷粉。当原料在1350℃熔融2h自然冷却后,再从室温以8℃／min的加热速度升温至750℃保温1h,然后再以4℃／min的升温速度升至960℃,保温2h后冷淬、粉碎、过筛得到牙用烤瓷粉。经XRD分析瓷粉中出现的晶体主要为白榴石晶体,且SEM观察到晶体分布均匀且尺寸较小(10μm^2左右)。结果表明：双相成核剂的引入,能有效的降低白榴石晶体在该体系的析晶温度和减小其晶体尺寸,这对于牙用烤瓷粉的制备和临床应用都具有一定的意义。在此基础上,初步探讨了此双相成核剂的作用原理。     

POY、FDY一体联合试验机纺FDY的工艺

用POY、FDY一体联合试验机纺制FDY,讨论了纺丝工艺条件对FDY的影响,通过调整工艺参数来优化FDY的质量,本次试纺的工艺条件：纺丝温度290℃左右,侧吹风风速约0．48m／s,风温23℃左右,卷绕速度为4050m／min,可纺出质量优良的FDY。     

2种形态铜绿假单胞菌在氯消毒过程中消毒副产物研究

为研究悬浮和附着生长下的铜绿假单胞菌经氯消毒后消毒副产物的生成情况,以无菌生理盐水模拟悬浮生长环境,选取镀锌材料建立附着生长模型,采用UFC法进行加氯试验,气相色谱分析。结果表明,2种形态下的铜绿假单胞菌均为消毒副产物前驱物质,主要副产物包括三卤甲烷(THMs)、三氯乙腈(TCAN)和水合三氯乙醛(CH),且THMs符合TOC含量、单位耗氯量大小关系,而TCAN和CH则相反,可能是由生物膜胞外聚合物中的某种蛋白质结构引起。Br-的存在对CHCl3和TCAN产生抑制作用,转而形成更多的CHBr3和二溴乙腈,当Br-的质量浓度为2 mg/L时,CHBr3和二溴乙腈含量达到最大值,且主要影响总THMs和卤乙腈的含量,溴氯甲烷和溴氯乙腈的含量均随Br-含量的增加而先升高后降低。     

SCRATCH HARDNESS TESTS OF CERAMIC MATERIALS1

Three sets of standards were prepared: (1) a set of minerals according to Mohs'Scale, (2) a set of steel samples, and (3) a set of Carboloy (tungsten carbide alloy) samples. The sets of standards were compared with each other according to their scratch hardness. Specimens of ceramic materials were then measured for scratch hardness with each set of standards. The results are compared.     

PERFORMANCE CHARACTERISTICS OF SINGLE-STAGE STEAM JET EJECTORS USING TWO SIMPLE MODELS

Two simple models, one of Hougen, Watson and Ragatz (HWR) and the other by Dotterweich and Mooney (DM), are used to compute the motive steam requirements of single-stage steam jet ejectors. Non-idealities associated with the performance of nozzle, diffuser and that of mixing process are accounted for by nozzle and diffuser efficiency factors. Nozzle and diffuser efficiencies between 0.7-0.9 and 0,75-1.0 respectively, are studied for systems, steam-water vapor, steam-air, and steam-hydrocarbons (n-paraffins: C₁ to C₅). The results are compared with the empirical correlations of Power and Ludwig. In addition, the effect of motive steam pressure on steam consumption is investigated. It is found that predicted steam consumptions, when DM model is employed, agree closely with literature data. It is suggested that model predicted values, rather than the empirical plots, be used in any specific case, since empirical correlations represent only averaged values.