科创中国

基于未改性Pt/Al2O3催化剂探索环己酮二聚物脱氢反应体系,针对反应产物的分布特点使用多种钾助剂对催化剂性能进行调变,采用吡啶吸附红外(Py-IR)、氢氧滴定(H2-O2 Titration,HOT)、X射线光电子能谱(XPS)、程序升温还原(TPR)等对Pt-K/Al2O3催化剂中钾助剂的促进作用机制进行研究.结果表明:在合适的条件下使用钾助剂可以大幅提高邻苯基苯酚(OPP)的选择性(最高可达94%);钾助剂对铂基脱氢催化剂的促进作用体现为2个方面,一是削弱氧化铝载体酸性,可以通过抑制酸中心导致的副产物生成而提高目的产物OPP的选择性,二是钾与铂中心存在较强的相互作用,特别是电性促进作用(EP);碱性较强的K2CO3改性效果最好.

石家庄市冶河灌区续建配套与节水改造工程项目自1998年立项以来,累计完成投资2.0亿元,改善了工程状况,提高用水效率,保障了区域粮食安全,促进了农业发展,拉动了地方经济.取得了良好的经济、社会和生态环境效益.随着国家对灌区投入的增加,冶河灌区将为夯实农业发展的水利基础方面做出更大贡献.

Lightweight design requires an accurate life prediction for structures and components under service loading histories. However, predicted life with the existing methods seems too conservative in some cases, leading to a heavy structure. Because these methods are established on the basis that load cycles would only cause fatigue damage, ignore the strengthening effect of loads. Based on Palmgren-Miner Rule(PMR), this paper introduces a new method for fatigue life prediction under service loadings by taking into account the strengthening effect of loads below the fatigue limit. In this method, the service loadings are classified into three categories: damaging load, strengthening load and none-effect load, and the process for fatigue life prediction is divided into two stages: stage I and stage II, according to the best strengthening number of cycles. During stage I, fatigue damage is calculated considering both the strengthening and damaging effect of load cycles. While during stage II, only the damaging effect is considered. To validate this method, fatigue lives of automobile half shaft and torsion beam rear axle are calculated based on the new method and traditional methods, such as PMR and Modified Miner Rule(MMR), and fatigue tests of the two components are conducted under service loading histories. The tests results show that the percentage errors of the predicted life with the new method to mean life of tests for the two components are –3.78% and –1.76% separately, much lesser than that with PMR and MMR. By considering the strengthening effect of loads below the fatigue limit, the new method can significantly improve the accuracy for fatigue life prediction. Thus lightweight design can be fully realized in the design stage.

目的:观察长脉冲1064nmNd:YAG激光治疗婴幼儿皮肤血管瘤临床疗效,并探讨影响疗效的相关因素.方法:应用长脉冲1064nmNd:YAG激光治疗婴幼儿皮肤血管瘤215例,其中鲜红斑痣19例,草莓状血管瘤179例,混合型血管瘤17例.分析其疗效与病变类型、瘤体大小、病变部位及治疗次数的关系.结果:215例患儿中治愈133例,显效67例.有效8例.无效7例,痊愈率和有效率分别为61.9%和93.1%.疗效与血管瘤的病变类型、瘤体的大小以及治疗次数有关,但与其病变部位无明显相关性.治疗后暂时性色素沉着、暂时性色素减退、浅表性瘢痕、头部毛发减少或消失的发生率分别为48.8%、8.3%、4.6%和3.7%.结论:长脉冲1064nmNd:YAG激光治疗婴幼儿皮肤血管瘤疗效好,安全性较高,不良反应轻,可在临床上推广使用.

During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12 Mo V. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

目的评价胃镜下氩离子凝固术联合质子泵抑制剂奥美拉唑治疗Barrett食管(BE)的长期临床疗效.方法对2009年1月~2011年1月我院胃镜室检查并经病理证实的Barrett食管患者59例,根据患者意愿分为两组.对照组31例,给予奥美拉唑20mg口服,每日1次;实验组在胃镜下行氩离子凝固术,术后给予奥美拉唑20mg口服,每日1次.两组患者进行随访.于术后3、6和12个月时复查胃镜,评价Barrett食管复发情况.结果治疗后3个月时对照组临床症状缓解例数为15例,缓解率为48.4%,实验组有缓解例数为22例,缓解率为78.6%,实验组明显高于对照组(Xz=5.72,P=0.01).对照组治疗前症状评分为(1.82±0.51)分,治疗后为(1.34±0.66)分;实验组治疗前症状评分为(1.83±0.46)分,治疗后为(0.81±0.28)分,实验组症状缓解明显好于对照组(t=3.94,P〈0.01).术后主要不良反应为胸骨后不适8例(28.6%),黏膜下气肿4例(14.3%)和发热3例(10.7%);随访12个月,实验组累及复发6例(6/28),累及复发率为21.4%.结论胃镜下氩离子凝固术联合奥美拉唑治疗Barrett安全可靠,短期疗效确切,长期随访存在一定的复发率.

There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.

随着石家庄市城市规模的扩大,越来越多的城市水文环境问题日益突出.在分析石家庄市目前水文环境的基础上,提出城市面临的水文问题:城市化进程的加快,对降水量、地下水位、灾害性天气、地表水环境、地下水水质等一系列水文参数产生影响,根据石家庄城市水文的特点,探讨其变化规律并采取相应的解决对策,对城市经济发展有重要意义.

注塑模设计过程中,冷却水道布局的好坏,关系到塑件的成型质量和成型周期.以某深腔塑件为例,阐述了CAE技术在注塑模冷却水道优化设计中的应用方法和意义.

为了评价各因素对大坝监测效应量的综合影响程度,提出一种新的灰色距离测度,并应用于大坝效应量分量比例确定中.首先利用主成分确定各分量真实系数,然后应用该理论确定各个分量的比例.工程实例表明,该方法简单可行,能科学有效地确定大坝效应量分量比例.