THE LOSS OF NON-METALLIC INCLUSIONS IN STEEL DURING ELECTROLYTIC SEPARATION

<正> 电解法分离钢中的非金属夹杂物已被确定为比较适合的方法之一,在苏联、我国以及有些别的国家都正广泛地采用着;可是最近Баталин和Розенфелд在考察电解法分离非金属夹杂物的准确性和适用性时,他们以硫酸亚铁为电解液,用铂作阳极,以纯MnO及流钢砖中渣膜作夹杂物,测出在电解过程中的损失量,最后得到的结果是前者几乎全部补溶解了,而后者的损失量也是很严重的,其中被溶解的MnO也达1/3以上。这个事实是不是就说明了电解分离钢中的夹杂物非常不可靠了呢,我们有进一步研究的必要。本文的目的仅说明非金属夹杂物在电解分离过程中被溶解的情形,但不能用以肯定电解分离及分析是完全可靠的,因为其中的其他步骤(如破坏碳化物)还可能引起严重的损失,我们还须要更深入的进行研究。     

DISTRIBUTION OF NON-METALLIC INCLUSIONS IN RIMMING STEEL INGOTS

本文根据鞍山钢铁公司沸腾钢的四种浇铸方案(一般,造渣,模口加盖,模口加盖铸完压板),在非金属夹杂物的类型和分布方面进行了金相的观察。结果指出,各种类型夹杂物都有它分布的特点。在这四种方案所浇铸的钢锭中基本上是一致的;惟在上述后三种操作方法所铸出的钢锭的上部发现沿晶粒间界析出的网状氧化物,可能影响钢锭的质量。文中就各种夹杂物的分布的特点进行了讨论,并对沸腾铜的生产提出了几点建议。     

THE EFFECT OF ALLOYING ELEMENTS ON AGE BRITTLENESS OF A Cr-Mn-C-N AUSTENITIC HEAT-RESISTANT STEEL

叙述并討論了合金元素对鉻錳碳氮奥氏体耐热鋼时效变脆的影响的初步实驗結果。結果指出钼釩促使这种类型鋼的变脆,硼能改善其时效脆性,适合于設計的要求。微量混合稀土元素对改善时效脆性的作用不明显。 金相和电子显微镜及X射线研究的結果指出,晶界和沿晶界边緣組織結构的变化是影响脆性的主要因素。时效后的主要沉淀为M_(23)C_6和(Cr,Fe)_2N;含钼較高的鋼种(>1％Mo),在更长时間的时效以后,有x相及σ相的出現,当其量較多时,也可增加鋼的脆性。硼不但減緩某些相的析出,而且也可以改变它們的分布状态,使晶界发生不連續沉淀,从而对韌性的降低較少。     

Parameter estimation of discrete systems via Hahn polynomials

This paper presents a procedure for using Hahn polynomials for the analysis and parameter estimation of linear discrete-time single-input/single-output systems described by difference equations. An advantage is gained through transforming a linear difference equation into a set of algebraic equations of the system parameters and the Hahn coefficients of the system variables. The key to the equation conversion is the derivation of a relation between the Hahn coefficients of a function and its time-shifted ones. Examples are provided to show the utilization of the procedure.     

Double Walsh series solution of first-order partial differential equations

A double Walsh series is introduced to represent approximately functions of two independent variables, and is then applied to analyse single as well as simultaneous first-order partial differential equations. The solutions for the coefficient matrices can be obtained directly from Kronecker product formulae, which are suitable for computer computation. An example for a single first-order partial differential equation is solved by a double Walsh series approximation with satisfactory results.     

碱金属硫酸盐沉积引起的铁基合金在中温下的热腐蚀

研究工业纯铁、Fe-Cr和Fe-Al合金有表面Na_2SO_4或Na_2SO_4-K_2SO_4沉积物时在含SO_3的富氧气氛中于中等温度区间的热腐蚀行为。研究结果表明,铁基合金在实验条件下发生的热腐蚀是由液态Na_2SO_4—Fe_2(SO_4)_3或Na_2SO_4-K_2SO_4-Fe_2(SO_4)_3共晶所致,其腐蚀行为与温度、气体组成、合金元素含量、沉积物组成有关。腐蚀形貌的观察表明,铁基合金热腐蚀的发展伴随着疏松的Fe_2O_3层的增厚和紧靠合金表面相对致密的氧化层的快速成长。在合金/氧化物     

PHYSICOCHEMICAL PROPERTIES OF GLUTEN-FREE PANCAKES FROM RICE AND SWEET POTATO FLOURS

Gluten‐free pancakes were prepared using rice flour and rice flour replaced with various amounts, at 10, 20 and 40%, of sweet potato flour. Textural properties of the cooked pancakes, such as hardness and chewiness generally increased with time after cooking, whereas they decreased with increased sweet potato flour replacement. On the other hand, cohesiveness decreased with time, but increased with increased sweet potato flour in the pancake. Nutritional properties of the rice–sweet potato pancakes, such as protein content, dietary fiber, total carbohydrate and calories were generally comparable with those of their wheat counterpart. The only significant difference was in the beta‐carotene content, which increased from 5.2 to 236.1 μg/g when sweet potato flour was incorporated, from 0 to 40%, into the rice pancake formulation.     

On the operational matrices of block pulse functions

It is pointed out that the mathematical bases for block pulse operational methods to various dynamic system problems are to represent the delay operator exp(— hs)approximately by and to represent exp ( — αhs) approximately by (1 — α) + α exp ( — hs), where 0 ≤ α ≤ 1. On these bases, all the existing block pulse operational matrices—the integration matrix, the convolution matrix, the correlation matrix, the delay matrix, and the stretch matrix—can be derived in a mathematically rigorous way without having to use graphical demonstrations.     

The shifted Legend re approach to non-linear system analysis and identification

Applications of the shifted Legendre polynomial expansion to the analysis and identification of the non-linear system described by a Hammerstein model which consists of a single-valued non-linearity followed by a linear plant are studied. For the analysis, by using the shifted Legendre polynomial expansion, the solution of a non-linear state equation is reduced to the solution of a linear algebraic matrix equation. For the identification, through the shifted Legendre expansions of the measured input-output data, the unknown parameters of both the linear plant and the characterization of the non-linear element are estimated using the least-squares method. Algorithms are presented. Numerical examples are given to illustrate the use of this approach.     

BUOYANCY EFFECTS ON THE FORCED CONVECTION ALONG VERTICALLY MOVING SURFACES

The buoyancy effects on the laminar boundary layer heat transfer from vertically moving flat plate and cylinder are studied by a coordinate perturbation method for the cases of prescribed surface temperature and prescribed wall heat flux. Universal expressions are given to show the temperature distributions and the increase of heat transfer rate with the increase of the buoyancy force parameter.