Ordinal optimization for a class of deterministic and stochasticdiscrete resource allocation problems

The authors consider a class of discrete resource allocation problems which are hard due to the combinatorial explosion of the feasible allocation search space. In addition, if no closed-form expressions are available for the cost function of interest, one needs to evaluate or (for stochastic environments) estimate the cost function through direct online observation or through simulation. For the deterministic version of this class of problems, the authors derive necessary and sufficient conditions for a globally optimal solution and present an online algorithm which they show to yield a global optimum. For the stochastic version, they show that an appropriately modified algorithm, analyzed as a Markov process, converges in probability to the global optimum, An important feature of this algorithm is that it is driven by ordinal estimates of a cost function, i.e., simple comparisons of estimates, rather than their cardinal values. They can therefore exploit the fast convergence properties of ordinal comparisons, as well as eliminate the need for “step size” parameters whose selection is always difficult in optimization schemes. An application to a stochastic discrete resource allocation problem is included, illustrating the main features of their approach     

HPLC-MS/MS法快速测定淀粉生物粘附材料特异性结合糖类物质的含量

研究了高效液相色谱-串联质谱(HPLC-MS/MS)法测定淀粉生物粘附材料与糖残基特异性结合实验中,岩藻糖、半乳糖、α-甲基甘露糖苷和N-乙酰葡萄糖胺4种糖类物质含量的分析方法。将反应后的样品直接离心过滤后即可利用HPLC-MS/MS进行定性定量分析。以V(乙腈)∶V(水)=80∶20的溶液作为液相色谱流动相,质谱采用电喷雾负离子电离方式扫描,以多反应监测(MRM)模式进行定量分析。在添加水平为1.0~40.0 mg.L-1范围内,岩藻糖的回收率为111.0%,相对标准偏差(RSD)为6.55%;在添加水平为1.0~80.0 mg.L-1范围内,半乳糖、α-甲基甘露糖苷和N-乙酰葡萄糖胺的回收率分别为106.5%、99.0%和91.0%,相对标准偏差分别为7.78%、6.64%和5.68%。4种糖类物质的方法检出限(S/N≥3)分别为0.1mg.L-1(岩藻糖),1.0 mg.L-1(半乳糖),0.1 mg.L-1(α-甲基甘露糖苷)和0.5 mg.L-1(N-乙酰葡萄糖胺)。该方法可用于评价淀粉粘附材料和糖类物质的特异性结合,为其他领域中糖类物质含量的测定提供可借鉴的方法。     

Y~(3+)掺杂ZnO压敏陶瓷的微结构和电性能研究

采用两步烧结法制备了Y3+掺杂的(以Y(NO3)3·6H2O形式加入)ZnO压敏陶瓷,通过XRD、SEM和EDX系统研究了Y3+掺杂量对ZnO压敏陶瓷微结构和电性能的影响。结果表明:随着Y3+掺杂量的增加,电位梯度VT和非线性系数α提高,晶粒尺寸减小,施主浓度Nd和晶界态密度Ns降低,势垒宽度ω增大。当掺杂的x[Y(NO3)3·6H2O]为1.2%、烧结温度为1100℃时,ZnO压敏陶瓷电性能最好,其VT为675V/mm,α为63.9,漏电流IL为2.40μA。     

叠烧对ZnO压敏电阻中Bi_2O_3挥发的控制

采用高能球磨法制备ZnO压敏电阻混合粉体。用XRD、SEM对其形貌和微观结构进行了表征。研究了叠烧烧结时,不同位置ZnO压敏电阻中Bi2O3的挥发情况及对其电性能的影响。结果表明:中心位置处ZnO压敏电阻的非线性系数为31,较表层提高100%;其漏电流为6.0μA,电位梯度为345V/mm。Bi2O3的挥发,呈现从中心到表层逐步加剧的趋势。     

工程量清单计价在市政排水建设工程中的应用

结合北京市某污水处理厂一期建设工程的实例,分析了工程量清单计价方法在实际应用中的关键环节和主要特点,对项目招投标阶段和施工过程中应当注意的造价管理问题进行了探讨,并给出一些工程量签证与风险控制的策略。     

鱼腥草黄酮抗抑郁活性的研究

采用高浓度皮质酮处理pc12细胞以模拟抑郁症病人脑神经元损伤状态;采用MTT法评价了鱼腥草黄酮的细胞毒性及其对皮质酮损伤的pc12细胞的保护作用;采用小鼠悬尾实验、小鼠强迫游泳实验,观察小鼠的不动时间,探讨鱼腥草黄酮的抗抑郁作用.结果表明,在最大无毒浓度128 μmol·L-1以内,鱼腥草黄酮对高浓度皮质酮损伤的pc12细胞有很明显的保护作用,最小有效浓度为1 μmol·L-1,细胞毒性等级为1级;在悬尾实验和强迫游泳实验中,128 mg·kg-1、64 mg·kg-1、32 mg·kg-1、16 mg·kg-1剂量组鱼腥草黄酮均能显著缩短小鼠不动时间.表明鱼腥草黄酮有明显的抗抑郁活性.     

Aqueous dispersion of 1D van der Waals Mo6S3I6 crystal using biocompatible tri-block copolymer

To achieve the stable dispersion of 1D van der Waals crystal Mo₆S₃I₆ in aqueous media, the tri-block copolymer (Poloxamer) is used as dispersant. The head group of Poloxamer, hydrophobic polypropylene oxide parts can be adsorbed to Mo₆S₃I₆ surface by hydrophobic interaction and the tail group with hydrophilic polyethylene oxide exposed to the outside of the Mo₆S₃I₆ is soluble in water and can form sufficient steric hindrance, resulting in stable aqueous dispersion in nm scale. The excellent biocompatibility of aqueous dispersed nm scale 1D Mo₆S₃I₆ was demonstrated by effective proliferation of C2C12 cells.     

DYNAMIC MODELLING FOR ROLLING SLIDEWAYS ASSEMBLY WITH DAMPING OIL-FILMS

ＤＹＮＡＭＩＣＭＯＤＥＬＬＩＮＧＦＯＲＲＯＬＬＩＮＧＳＬＩＤＥＷＡＹＳＡＳＳＥＭＢＬＹＷＩＴＨＤＡＭＰＩＮＧＯＩＬ－ＦＩＬＭＳ．ＤＹＮＡＭＩＣＭＯＤＥＬＬＩＮＧＦＯＲＲＯＬＬＩＮＧＳＬＩＤＥＷＡＹＳＡＳＳＥＭＢＬＹＷＩＴＨＤＡＭＰＩＮＧＯＩＬ－ＦＩＬ...     

碳纳米管对激光选区熔化成形Al基复合材料的影响

基于激光选区熔化（SLM）方式,通过改变扫描速度,制备不同碳纳米管（CNTs,质量分数分别为0、0.5wt%、1.0wt%、1.5wt%、2.0wt%）含量的CNTs/Al复合材料试件,探究不同CNTs含量与激光扫描速度对试件性能的影响。结果表明,CNTs含量小于1.0wt%时,分散效果较好,大部分CNTs以单根状态黏附于Al粉表面;含量大于1.0wt%时,CNTs团聚尺寸增大、数量增多。相同SLM成形工艺下,低CNTs含量的CNTs/Al复合材料试件内部孔隙较少,致密度较高;高CNTs含量的CNTs/Al复合材料试件内部孔隙逐渐增多,致密度降低。激光扫描速度为1 300 mm/s工艺下,随着CNTs质量分数的增加,CNTs/Al复合材料试件硬度呈先上升后下降趋势,在CNTs含量为1.0wt%显微硬度达到最高。CNTs/Al复合材料试件平均晶粒尺寸相对于铝合金试件更加细化,在CNTs含量大于1.0wt%时,尽管晶粒依然细化,但试件致密度降低造成显微硬度下降明显。