中碳碳素结构钢S55C的球化退火工艺

对S55C钢进行了不同工艺的球化退火处理,研究了所获得的组织和硬度.结果表明,S55C钢经740℃保温5 h,以≤20℃/h的冷速缓冷至700℃保温5 h,再以≤40℃/h的冷速缓冷至680℃保温5 h后空冷,得到的组织为球状珠光体,珠光体球化率≥90％,硬度值165 HBW,符合客户使用要求.     

55SiCr钢悬架弹簧尺寸超差原因分析

某55SiCr钢悬架弹簧在卷制过程中部分弹簧尺寸超过公差允许范围,采用光学显微镜、电子探针和X射线衍射仪对弹簧尺寸超差的原因进行了分析。结果表明,尺寸超差弹簧用55SiCr钢线热处理过程中冷却不足导致其含有过多残留奥氏体,是弹簧产生尺寸超差的原因。通过降低冷却水温度,能够有效降低钢线中残留奥氏体的含量。     

USB Host的应用研究

文章采用以U盘为USB设备和AT89C55单片机作为嵌入式系统的核心MCU,采用中断任务调度机制设计软件系统,设计并实现了基于USB Host接口芯片SL811HS建立了可与U盘进行通信的通用USB Host嵌入式系统模块。该模块能脱离PC,直接与传统的USB外设进行通信。将USB Host应用在HPDesk系列打印机中,实现USB主机系统的构建,并对开发嵌入式USB主机,使USB应用脱离PC具有普遍意义。     

汽车螺旋悬架弹簧用钢55SiCrA组织和性能研究

采用热膨胀法结合显微金相与硬度法,在LINSEIS L78 RITA相变仪上测定了55Si Cr A弹簧钢的临界点温度和连续冷却转变曲线,研究了冷却速度对组织和硬度的影响规律。在此基础上,进行了控轧控冷工业试验。结果表明,当冷速≤2℃/s时,转变产物为少量铁素体、珠光体,珠光体硬度随冷速增大而增大;当冷速≥5℃/s时,转变产物为珠光体、马氏体;当冷速≥20℃/s时,转变产物为马氏体,硬度随冷速增大而增大;现场控轧控冷的试验钢抗拉强度达到1 163 MPa,伸长率为13%,面缩率为49%,综合力学性能良好,满足了用户的使用要求。     

Improved Generation of Minimal Addition Chains

An addition chain for a natural number n is a sequence 1=a ₀<a ₁< . . . <a _r =n of numbers such that for each 0<i≤r, a _i =a _j +a _k for some 0≤k≤j<i. An improvement by a factor of 2 in the generation of all minimal (or one) addition chains is achieved by finding sufficient conditions for star steps, computing what we will call nonstar lower bound in a minimal addition and omitting the sorting step.     

高速公路护栏钢基表面热镀55Al-Zn合金生产中的关键技术研究

探讨了电解活化助镀剂法热镀55Al-Zn合金制备高速公路护栏防腐镀层的方法，并对构成整个工艺的2项关键技术-助镀剂及合金熔炉进行了研究，给出了工业上可行的解决方案。工业生产表明，该方法可顺利地进行生产。     

Digitalization and CO2 emissions: Dynamics under R&D and technology innovation regimes

New digital technologies help to curtail those that are carbon intensive but are accompanied by CO₂ emissions due to their own energy demand. Whether digitalization relates to increased or decreased carbon emissions may depend on the sophistication of an economy's research and development (R&D) output. This study explores the R&D-induced regime transition that governs the relationship between digitalization and CO₂ emissions. The study seeks evidence of the environmental Kuznets curve hypothesis and tests it with a panel smooth transition regression (PSTR). Employing this estimator with two R&D output regimes makes it possible to account for year- and country-varying effects of digitalization, human capital, and country income level on CO₂ emission. The research covers 55 high- and middle-income economies from 1996 to 2019. The paper finds that the transition process is driven by R&D output level – measured in technology patents per country inhabitants. The findings support the environmental Kuznets curve hypothesis and confirm that CO₂ emissions have an inverted U-shaped relationship with digitalization and income level. This nonlinear relationship transitions smoothly in the exogenous R&D output level. The digitalization indicator in the lower R&D regime has a significant point estimate of 0.07; in the higher regime, the estimate is −0.14. The R&D output threshold at which the transition function switches between the two regimes corresponds to a level of 39.9 technology patents per million inhabitants.     

Acceptance of technology related to healthcare among older Korean adults in rural areas: A mixed-method study

Many older adults find it difficult to accept new forms of information and communication technology (ICT), despite its advantages such as convenience and efficiency. It is necessary to identify the reasons for low ICT use among older people—even among those with positive attitudes toward ICT—to help older adults cope with social changes and bridge the digital divide. This study explored technology acceptance and related factors among older Korean adults living in rural areas. Based on an existing model (the senior technology acceptance model), a new conceptual framework for technology acceptance was proposed, and the framework was tested using pathway analysis. Semi-structured interviews were conducted in three focus groups (n = 15), and a survey questionnaire was administered to older Korean adults living in a rural area (n = 233) from 17 January 2021 to 18 February 2021. Qualitative data were analyzed using directed content analysis, and quantitative data were analyzed using pathway analysis. Four categories, 11 subcategories, and 18 codes were identified, and a new conceptual framework was proposed based on the qualitative findings. The results of the model revealed significant positive direct paths from external controls (β = 0.45, p < .001), attitudinal beliefs (β = 0.33, p < .001), and cognitive health (β = 0.10, p = .040) to internal abilities. It is necessary to develop and apply a targeted and tailored ICT education program to improve self-efficacy and reduce anxiety regarding technology use among older Korean adults living in rural areas.