Restricted compositions and permutations: From old to new Gray codes

Any Gray code for a set of combinatorial objects defines a total order relation on this set: x is less than y if and only if y occurs after x in the Gray code list. Let ? denote the order relation induced by the classical Gray code for the product set (the natural extension of the Binary Reflected Gray Code to k-ary tuples). The restriction of ? to the set of compositions and bounded compositions gives known Gray codes for those sets. Here we show that ? restricted to the set of bounded compositions of an interval yields still a Gray code. An n-composition of an interval is an n-tuple of integers whose sum lies between two integers; and the set of bounded n-compositions of an interval simultaneously generalizes product set and compositions of an integer, and so ? put under a single roof all these Gray codes.As a byproduct we obtain Gray codes for permutations with a number of inversions lying between two integers, and with even/odd number of inversions or cycles. Such particular classes of permutations are used to solve some computational difficult problems.     

国内城市生活垃圾特性及其处理技术研究

根据我国生活垃圾的构成情况,对国内部分城市生活垃圾的特性进行了分析,结果表明,近年来,国内城市生活垃圾不仅产量有了明显提高,垃圾构成也发生了很大的变化,其中有机物、可燃物和可回收利用成分增加;垃圾热值相应提高,部分城市生活垃圾的热值达到5000kJ/kg左右。     

邢钢竖炉球团采用不同原料搭配的生产实践

邢钢两座8m^2竖炉自投产以来，采用了不同原料搭配生产球团矿，并取得了一定经验，本文对各种原料搭配的生产情况进行了分析和总结。     

基于WEB模式招投标决策系统的分析与研究

介绍了目前设备采购招投标的现状与存在的问题，并分析和建立了网上招投标系统的体系结构、网络架构和功能结构。利用决策支持系统理论中的层次分析法评定中标企业，该层次分析法思想简洁、使用灵活，能够成功地应用于中标方的评定，特别是对于缺少定量数据进行定性判断的情况。在此基础上，开发出了基于WEB模式采购招投标系统，经实际应用，该招标系统与传统的招标管理相比，充分体现招投标工作的“透明”特征，发扬“公平、公开、公正”的原则。     

Chemical compositions and some physical properties of the water and alkali-extracted mucilage from the young fronds of Asplenium australasicum (J. Sm.) Hook

Effect of extraction conditions, including solvent types (water and sodium bicarbonate) and extraction temperatures (25, 50, 70 and 90 °C), on the physicochemical properties of the water and alkali-extracted mucilage from the young fronds of Asplenium australasicum (J. Sm.) Hook was evaluated. It was found that sodium bicarbonate extract generally showed higher yield than water extract, and its yield increased with increasing extraction temperature. Composition analysis revealed that A. australasicum mucilage was composed of mainly carbohydrates in conjunction with some glycoproteins. The weight average molecular size of the carbohydrate fraction of crude mucilage obtained from alkali and water extractions were about 6.30 × 10⁷ and 2.63 × 10⁷, respectively. Sugar composition analysis revealed that A. australasicum young fronds mucilage contained significant amount of uronic acid (14.3-56.6% based on total sugars). For the water extracted mucilage, GlcA is predominant. However, for the sodium bicarbonate extracted mucilage, GalA is predominant. Furthermore, Rha can only be detected in sodium bicarbonate extract. Other major neutral sugars include Gal, Man, Xyl and Fuc. The intrinsic viscosity of the water and alkali-extracted mucilage in deionized water were around 21.12 and 5.92 dL/g, respectively. This information would be useful when considering A. australasicum young fronds mucilage as a new Agro-ingredient.     

Geochemical characteristics of major and trace elements in Sahinali Coals,Aydin, Turkey

In this study, geochemical behavior of elements is investigated in 25 coal samples collected at 10 locations of ?ahinli coaliferous units at southeast of Ayd?n, Turkey. In all the samples, X-ray powder diffraction and inductively coupled plasma mass spectrometry analyses were performed and element and mineral compositions were determined. Total organic carbon (TOC) values of coals are between 14.6 and 37.7 wt% with average of 28.5 wt%. Samples are composed of quartz, calcite, feldspar, dolomite, mica, gypsum, and salt minerals which are accompanied by illite-, kaolinite-, and smectite-type clay minerals. Comparison of average element contents of world coals and studied samples yields that K > Fe > As > U > Cs > Y > Er > Al > Th > Rb > Yb > W > Tb > Dy > Lu > Ce > Sm > La > Ho > Si > Nd > Gd > Tm > Eu > Nb > Pr > Pb > Sn > Ni > Cu > Ga > Ta > Sb > Zr > Cd > V > Zn > Co > Mo > P > Hf > Ba are found to be enriched, while Mn > Be > Ca > Sr > Bi > Mg are found to be depleted. Statistically elements are correlated with TOC.     

挤压温度对Mg-6Zn-1Mn-4Sn-0.5Y镁合金组织和性能的影响

通过光学显微镜（OM）,X 射线衍射（XRD）,扫描电子显微镜（SEM）,电子背散射衍射（EBSD）以及拉伸试验对360和420℃挤压的Mg-6Zn-1Mn-4Sn-0.5Y变形镁合金的组织和性能进行了研究。研究结果表明,合金铸态和时效态的相组成为α-Mg, Mn, Mg7Zn3, Mg2Sn, 和 MgSnY相。挤压温度从360℃增加到420℃,动态再结晶完成,晶粒长大,合金的屈服强度,抗拉强度以及延伸率分别由259MPa, 350MPa 和 18.3% 降低至 239MPa, 332MPa和12.5%。理论计算和拉伸试验结果表明,细晶强化和固溶强化对合金屈服强度的增加产生决定性影响。     

甲醇制烯烃催化剂积炭的形成机理

采用二氯甲烷超声波萃取,提取甲醇制烯烃(MTO)待生催化剂和不完全再生催化剂外表面可溶性积炭,采用氢氟酸溶解及碳酸钠溶液中和后再用二氯甲烷超声波萃取,提取待生催化剂和不完全再生催化剂孔道内可溶性积炭,结合气相色谱-质谱(GC-MS)分析了其组成,并对MTO催化剂积炭形成的机理和再生烧炭的机理进行了分析探讨。结果表明:MTO待生催化剂外表面可溶性积炭主要是饱和烃和芳烃,其中饱和烃以C23~C31的正构烷烃为主,芳烃以一环和二环芳烃为主;孔道内可溶性积炭均为芳烃,以三环和四环芳烃为主,从质谱峰强度计算约占总量的80%,菲和芘约占总量的50%。MTO不完全再生催化剂外表面可溶性积炭主要是沸点较高的C23~C31正构烷烃;孔道内可溶性积炭主要是几个高含量组分如芘和菲等的残留。在催化剂外表面的饱和烃可能是由小分子烯烃类化合物经过一系列聚合而成,而催化剂外表面的一环和二环芳烃应该是从分子筛孔道内形成并溢出,在分子筛孔道口吸附。分子筛催化剂孔道内的多环芳烃,是由小分子烃类化合物经过一系列低聚、氢转移、环化和脱氢等反应生成。     

含铅固废协同冶炼过程PbO-CaO-SiO2-Fe2O3-ZnO五元渣系相平衡研究

在1 000~1 250 ℃范围内,采用高温平衡-淬冷-EDS方法研究了含铅固废协同冶炼过程PbO-CaO-SiO₂-Fe₂O₃-ZnO五元渣系在空气气氛下的相平衡规律。研究结果表明,渣中存在的主要物相有尖晶石(Zn_xFe_3-yO_4+z)、红锌矿(ZnO)、黄长石(Pb_vCa_2-vZn_wSi₂O₇)、赤铁矿(Fe₂O₃)、磁铁铅矿(PbFe₁₀O₁₆)和硅钙石(Ca_2-tPb_tSiO₄)。在1 250 ℃、1 200 ℃、1 170 ℃、1 130 ℃和1 100 ℃下,PbO-CaO-SiO₂-Fe₂O₃-ZnO体系的液相点分布测试结果与MTDATA6.0软件模拟液相线基本吻合。在1 000~1 250 ℃范围内,随着结晶过程的进行,PbO-CaO-SiO₂-Fe₂O₃-ZnO体系液相成分中Fe₂O₃含量从16.83%减少到7.67%,ZnO含量从7.62%减少到2.98%,(PbO+CaO+SiO₂)含量从75.55%增加到89.36%。     

SPME/GC/MS对比分析不同年份陈皮挥发性成分

利用固相微萃取/气相色谱/质谱联用技术对产自福建的、不同存放年份陈皮的挥发性成分进行了对比分析。结果显示,存放年份对陈皮挥发性成分的种类没有影响,但对各组分质量分数的影响有很大的不同。随存放时间的增加,陈皮挥发性成分的总量有所降低,主要成分柠檬烯的质量分数会增加,香柠檬烯、散花烃等组分的含量也会增加,但β-芳樟醇、α-松油醇、2-甲氨基安息香酸甲酯、α-法呢烯等成分的含量会降低,其余组分变化不大。