Sickle bush (Dichrostachys cinerea L.) field performance and physical–chemical property assessment for energy purposes

The sickle bush (Dichrostachys cinerea (L.) Wight & Arn.) comprises a woody legume shrub which is widely distributed throughout of the tropical areas of Africa, Asia and Oceania, being found as well in Cuba where it represents a difficult to control invasive plant. It holds great silvopasture and energy crop potentials. In southwestern Spain a two year field trial was conducted contemplating also another six hardwood taxa commonly used as energy crops. The sickle bush above ground dry biomass fraction was 60.4%; sickle bush displayed a high transpiration rate during hot days (3.02 kg m⁻² d⁻¹ to 6.82 kg m⁻² d⁻¹); cold winter temperatures (<−2 °C) together with hot and dry summer air (<20% relative humidity) committed survival and growth. The physical-chemical wood properties and the pellets thereof derived were analyzed and compared to those of the other energy crop taxa. The within other woody species normal chemical composition range coupled to a high wood density and energetic use properties (19.2 MJ kg⁻¹ higher heating value, 29 g kg⁻¹ ash content) all allow for an industrial use. Pellets evidenced also good physical and mechanical properties (690 kg m⁻³ bulk density, 42 g kg⁻¹ moisture content). However, the mechanical durability (93.9%) was slightly less than that required by the non-industrial use standards, therefore further improvements should be studied. All of the above could encourage scrubland cuts in Cuba as a mechanical control method, in addition to the expansion of plantations within of their tropical climate based natural habitats.     

改进支持向量机模型的旋转机械故障诊断方法

针对支持向量机在旋转机械的故障诊断中存在的模型超参数选择的不确定性,利用超参数相关理论和先验知识界定模型超参数选择区间,结合全局搜索和局部搜索实现参数优化组合,运用泛化模式搜索的模型超参数选择方法,并将改进的支持向量机模型引入旋转机械的故障诊断。结果表明,改进的模型具有较高的搜索效率和参数优化选择性能,提高了故障诊断的精度。     

酸改性坡缕石对Cu2+的吸附性能研究

坡缕石是一种含水富镁铝硅酸盐黏土矿物,具有独特的链层状晶体结构,在胶体、催化、吸附等众多领域表现出了优异的应用性能。本研究采用不同种类酸改性坡缕石,溶出八面体中阳离子的方式调控坡缕石结构,以Cu²⁺作为目标污染物,采用静态吸附实验研究了不同改性条件对坡缕石吸附Cu²⁺的影响规律。采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、N₂吸附、固体核磁共振(NMR)和热重(TG)等测试对改性前后坡缕石的结构进行了表征。研究结果表明,酸改性后的坡缕石杂质减少且微孔容积增大,对Cu²⁺的吸附能力也显著提高。反应时间为120 min、反应温度为60 ℃、溶液pH值为7的盐酸改性坡缕石对Cu²⁺吸附效果最佳,最大吸附量为70.64 mg/g。本研究结果对坡缕石在环境治理领域的应用具有重要研究意义。     

南方区域电网中长期电力统一交易模式设计

为了通过市场手段促进区域层面资源优化配置,实现南方区域省间电力资源余缺调剂,基于南方区域各省电力市场建设情况,提出符合南方区域统一电力市场建设的南方区域中长期电力交易基本规则的设计,设计内容包括市场管理、中长期交易机制、衔接机制以及适应现货市场的交易结算机制.该规则设计结合南方区域的经济发展结构、能源分布特点,在最大程...     

Fully computable bounds for a staggered discontinuous Galerkin method for the Stokes equations

We first propose a guaranteed upper bound for an arbitrary order staggered discontinuous Galerkin (staggered DG) method for the Stokes equations with the use of the global inf–sup constant. Equilibrated stress reconstruction and velocity reconstruction are the main ingredients in the construction of the error estimator. Next, to improve the error estimation and to overcome the difficulties caused by the calculation of the global inf–sup constant, a refined error control relying on local inf–sup constants is also developed. Some minimization techniques and an explicit method are then established to facilitate the construction of the refined error control. Finally, some benchmark examples are tested to compare the performances of the proposed error estimators.     

纳米碳酸钙掺杂纤维素基水凝胶制备及其对铜离子吸附性能研究

天然纤维素基水凝胶具有较强的吸附性能;是一种去除重金属离子的优良吸附剂;但凝胶强度较弱。通过自由基聚合反应;将丙烯酸（AA）、丙烯酰胺（AM）接枝在羧甲基纤维素钠（CMC）上;并进一步将自制的纳米碳酸钙（NCC）掺杂到纤维素水凝胶中;成功制备了NCC/CMC复合水凝胶。抗压性能测试结果表明;当NCC质量分数为2.5%、最大应变为80%时;最大应力为48.52 kPa;经20次循环后仍可达39.64 kPa。采用SEM、FT-IR、XRD和N₂吸附-脱附等实验对水凝胶形貌和结构进行表征分析;结果表明复合水凝胶具有丰富的表面多孔结构;比表面积为7.775 m²/g;属于介孔材料。考察了pH、铜离子溶液初始质量浓度和温度等因素对铜离子吸附量的影响。结果表明;当铜离子溶液pH为5.5、温度为30 ℃、铜离子溶液初始质量浓度为150 mg/L时;对铜离子的最大吸附量达到178 mg/g;吸附容量较CMC水凝胶提高了30 mg/g;吸附过程符合Langmuir吸附等温模型和准二级动力学模型。经过5次连续的吸附-脱附后;复合水凝胶仍具有良好的再生性能。