Structural and mechanical characteristics of porous 316L stainless steel fabricated by indirect selective laser sintering

Selective laser sintering (SLS) technique is capable of rapidly fabricating customized implants with porous structure. A simple encapsulation process was developed to coat 316L stainless steel (316L SS) powder with ethylene-vinyl acetate copolymer (EVA). Subsequently, porous 316L SS was prepared by SLS preforming of EVA-coated metal powders, debinding and sintering in hydrogen atmosphere. The effects of processing parameters on pore characteristics and mechanical properties were analyzed. The results indicate that the porosity of green body mainly depends on laser energy density, while the pore features and mechanical properties of sintered specimens are largely dominated by sintering temperature. After sintering at 1100–1300 °C, the average pore size and porosity are 160–35 μm and 58–28%, respectively. In addition, the elastic modulus and compressive yield strength are 1.58–6.64 GPa and 15.5–52.8 MPa, respectively. It is revealed that the pore structural parameters and mechanical properties of the as-sintered porous 316L SS can be controlled readily to match with those of cancellous bone by modification of SLS processing parameters and subsequent sintering temperature.     

Chinese university students’ knowledge and attitudes regarding forest bio-energy

The present study examines Chinese university students’ attitudes and knowledge regarding energy, specifically towards forest bio-energy in their country. The study was based on opinions of students from Northwest Agriculture and Forestry University (NWAFU) in China and it was conducted using a questionnaire completed by 441 students. The students’ attitudes are seen as highly relevant because they are considered as both potential consumers and possible experts in the field of bio-energy. Their activities influence how the future energy markets will likely develop. The results revealed various interesting facets of the students’ views regarding energy usage. Of particular interest is the students’ positive attitude towards renewable energy in general, but slightly less positive towards forest bio-energy. However, the respondents expected to receive more information and knowledge about renewable energy and forest bio-energy. Moreover, it can be concluded that the dissemination of knowledge through different sources (e.g. teaching in school, information available on the Internet and other media channels) is an increasingly important aspect regarding energy issues. The results of this study can provide information of the perceptions of young educated people on energy policy issues and thus serve political decision-making processes for the future options concerning the development of forest bio-energy in China. Finally, the outcome of this study indicates that further environmental and energy education in China is urgently needed.     

市政道路路面的养护及维修技术探析

在如今经济飞速发展的时代,道路已经变得非常重要。因此,我们对道路的维护就显得十分重要,首先要学会怎样保护好道路,尽量延长它的使用寿命,要运用科学的手段对道路进行维护,达到流畅的程度。本文研究了路面维修相关理论,查阅过大量资料,并且深入探讨过,所以笔者的观点还是具有代表性的。     

连铸坯轧板探伤不合的原因及采取的工艺措施

本文着重对舞钢连铸坯轧板产生探伤不合的原因进行分析，阐述了钢中夹杂物和铸坯凝固过程中的偏析对探伤因素的影响，从而在生产过程中采取相庆的措施，使钢板探伤合格率得到有效的提高。     

聚(苯乙烯-丙烯酸)载体铁组成因素对其催化活性的影响

制备了不同铁含量、不同功能团含量的聚 (苯乙烯丙烯酸 )铁配合物 ( SAAC· Fe)。考查了 Fe含量和功能团 ( COOH)含量与催化活性的关系。发现当 COOH含量在 1 .7～ 3.6mmol/g范围内 ,Fe/COOH(摩尔比 )在 0 .2时催化活性最高。聚丁二烯的微观结构不受上述因素的影响     

定量求解重力谷糙分离机工作面上物料的运动

定量求解重力谷糙分离机工作面上物料的运动较为困难，迄今尚未见有文献报道，但这一问题可采用解析和数值解结合的方法求解。文中详细介绍了具体步骤和实例计算结果。     

喷射混凝土在配合TBM法施工支护中的配制与应用

喷射混凝土作为洞挖工程的重要支护措施,在全国很多大型水利工程中被广泛应用,但与TBM隧洞掘进机配合应用在东北尚属首次.本文对喷射混凝土原材料的选择、配合比参数进行设计,提出适合本地区、本工程的喷射混凝土最优配合比.     

高速钢的红硬性

测定了6种高速钢的红硬性，结果发现高速钢的红硬性主要决定于淬火加热时溶入奥氏体中的碳化物的量，Co只能提高二次硬化效应，但不能提高红硬性，600℃以上，M42的 红硬性低于M2Si－4及M2Al。     

Thermal Conductivity of Monazite-Type REPO4 (RE=La, Ce, Nd, Sm, Eu, Gd)

Low-thermal conductivity ceramics in monazite-type REPO₄ (RE=La, Ce, Nd, Sm, Eu, Gd) ceramics are expected to have potential in structural (refractories, thermal insulator) and nuclear applications. To this end, the present study determines their thermal conductivities and examines how differences of the rare earth ions change their thermal conductivity at different temperatures. The results show that their conductivities are remarkably low from 25° to 1000°C. In addition, different conductivity variation mechanisms exist that change gradually upon altering from LaPO₄ to GdPO₄ at low and high temperatures. At relatively lower temperatures (≤400°C), the thermal conductivities of all the REPO₄ ceramics decrease nearly at first, reach a minimum value, and then rise with gradual altering from LaPO₄ to GdPO₄. It may be due to the combined effects of the increase of both the anharmonicities in lattice vibrations and the bond strength. As the temperature increases, the conductivity trends become obscure, and the conductivities of the monazite-type REPO₄ approach their minimum thermal conductivities when the temperature is above 800°C.     

Consequence calculation for relocation after nuclear accidents

This paper presents the results of dose and cost calculation for relocation after nuclear accidents. In order to quantify the relationship between radiation dose and relevant parameters defining protective actions, well-designed calculations have been performed and the results analyzed. On the basis of this, some dependencies between the important parameters describing the features of relocation and decontamination have been mathematically formulated. The similar has also been done for some economic costs as a result of implementing the countermeasures considered in this paper.