Self-healing,elastic and deformable novel composite phase change polymer based on thermoplastic elastomer SEBS for wearable devices

Journal of Materials Science - Form-stable composite phase change materials (C-PCMs) prepared by microencapsulation method and porous matrix adsorption method need for compression molding after...     

Aqueous-based,high-density nanoporous carbon xerogels with high specific surface area for supercapacitors

Journal of Porous Materials - Electrode materials with high density for assembling supercapacitors with high volumetric capacitance are urgently needed. Herein, nanoporous carbon xerogels (NPCXs)...     

融合环境因素的有限空间毒气扩散危害程度分析

为探究环境因素对毒气扩散危害程度的影响,通过对比有限空间内外环境差异,了解气体在有限空间内受力情况,并以传统高斯烟羽模型为基础,考虑扩散气体与有限空间边界碰撞产生的反射作用,建立了适用于有限空间气体扩散的改进高斯烟羽模型。深度剖析有限空间气体扩散环境,挖掘气体扩散主要关联因子,构建风速、地表粗糙度对有限空间气体扩散的影响函数;参照有限空间环境特征,分别设置3种不同风速与2种不同地表粗糙度,推求6种不同环境条件下气体扩散面积,阐明风速与地表粗糙度对有限空间气体扩散的影响程度。结果表明:在单一风速条件下,风速越高,地表粗糙度越低,洞室内H2S气体滞留时间越短,洞室内气体的扩散面积越小;风速越低,地表粗糙度越高,洞室内气体的扩散面积越大。     

Design and analysis of a class of redundant collaborative manipulators with 2D large rotational angles

The parallel spindle heads with high rotational capability are demanded in the area of multi-axis machine tools and 3D printers. This paper focuses on designing a class of 2R1T (R: Rotation; T: Translation) parallel spindle heads and the corresponding collaborative 5-axis manipulators with 2-dimension (2D) large rotational angles. In order to construct 2D rotational degrees of freedom (DOFs), a platform with 2D revolute joints is proposed first. Based on the constraint screw theory, the feasible limbs that can be connected in the platform are synthesized. In order to provide constant rotational axis for the platform, a class of redundant limbs are designed. A class of redundant 2R1T parallel spindle heads is obtained by connecting the redundant limbs with the platform and the redundant characteristics are verified by the modified Grübler-Kutzbach criterion. The corresponding 5-axis collaborative manipulators are presented by constructing a 2-DOF series translational bottom moving platform. The inverse kinematics and the orientation workspace as well as the decoupling characteristics of this type of 2R1T parallel spindle heads are analyzed. The results show that these manipulators have large 2D rotational angles than the traditional A3/Z3 heads and can be potentially used in the application of multi-axis machine tools and the 3D printers.     

β‐Cyclodextrin modified cationic acrylamide polymers for flocculating waste drilling fluids

In this article, the P(AM/A‐β‐CD/DMDAAC) is used as flocculant. The synthesis and characterization of the cationic polyacrylamide flocculant modified by β‐cyclodextrin have been studied in the early article. This article stresses its excellent flocculated performance and mechanism. In the flocculated process, the bridging flocculation played a dominant role. Through the flocculation experiments, it can be seen that the flocculating rate of the P(AM/A‐β‐CD/DMDAAC) on four solutions can go up to 93.4%, 89.7%, 85.1%, and 96.7%, respectively. As can be seen from experiment data, the flocculated property of P(AM/A‐β‐CD/DMDAAC) is superior to polyacrylamide and poly (dimethyl diallyl ammonium chloride). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40197.     

填海造地区域绿地系统存量修补策略研究 ——以天津市滨海新区绿地系统为例

国内多数滨海城市的填海造地历程 曲折,均经历过粗放式的“野蛮生长”过程, 到如今填海造地区域土地已渐趋饱和状态。 但是,由于过去的土地错位发展,其绿地系 统普遍存在规模不连续、开放共享性不足、 生态脆弱、防灾性能差这四类问题。以天津 市滨海新区填海区域土地利用与绿地系统为 例,提出建立“存量绿色土地库”,对填海造 地区域的存量土地进行生态修补。     

(Nd_(0.7)Pr_(0.3))_(60-x)Fe_(30)Al_(10)Cu_x(x=0,1,2,4)大块非晶合金磁性及矫顽力机理

采用铜模吸铸法制备了(Nd0.7Pr0.3)60-x Fe30Al10Cux(x=0,1,2,4)大块非晶合金,利用振动样品磁强计(VSM)研究了该合金的磁性能和磁粘滞行为。结果表明,这几种合金都呈现出较好的硬磁性。随着Cu元素的添加,矫顽力略有增加,但是合金的剩磁却没有变化。利用扫描速率法研究了(Nd0.7Pr0.3)60-x Fe30Al10Cux(x=0,1,2,4)大块非晶合金的磁粘滞行为,得到了这几种合金的相关磁性参数:热扰动场Hf为12.1~15.2 m T,热激活体积va为1.5×10-18~1.9×10-18 cm3。在所研究的合金中都存在明显的铁磁交换耦合作用,同时矫顽力与温度之间的关系符合Gaunt提出的畴壁钉扎模型,合金的硬磁性可能是这两方面共同作用的结果。     

Effects of combustor size and filling condition on stability limits of premixed H2‐air flames in planar microcombustors

An experimental study on stability limits of premixed hydrogen‐air flames in planar microcombustors (H = 1 mm and 1.5 mm) partially filled with porous medium is carried out, focusing on the effects of combustor sizes and filling conditions. Critical conditions for blow‐off, flashback, and breaking through the porous medium are experimentally measured. The blow‐off limits are nearly independent of combustor sizes and filling conditions, while the flashback limits are strongly influenced by the combustor size and the filling conditions. Critical values for breaking through are identified with two different methods, and it is shown that standing combustion waves are settled over a range of velocities, instead of a fixed value of filtration velocity, which is considered an important characteristic of microcombustion. Most results can be explained by the classic boundary velocity gradient theory by von Elbe and Lewis, and thus the validity of the theory to the present channel spacings is confirmed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2571–2580, 2015     

Adjustable insulation for enhancing the performance of phase change materials in buildings

The energy savings of a building roof integrated with a phase change material (PCM) and different insulation strategies are presented in this paper. The proposed roof structure includes a concrete slab with a PCM layer and an air cavity insulation, which can be adjusted according to certain strategies. The adjustable insulation is devised to enable a reduced total heat gain throughout 24 h in summer days, thereby improving the performance of the PCM. The heat gain/loss through the roof with the PCM layer and adjustable insulation is compared with that of the roof with the PCM layer and fixed insulation during a typical year in Hangzhou, China. The effects and optimization of the melting temperature of the PCM are also explored. The simulation results show that, overall, the adjustable insulation can reduce the daily heat flux through the roof by approximately 20% compared with the conventional fixed insulation.     

强碱型活性白土生物柴油合成催化剂的制备及其应用

提出了一种强碱型活性白土催化剂的制备方法,并将此催化剂用于催化油脂的酯交换反应合成生物柴油。首先在活性白土载体上负载氢氧化钙,覆盖活性白土的酸活性中心并提供弱碱中心,然后在弱碱中心上负载氢氧化钠活性组分制备了负载固体碱催化剂。实验结果表明,氢氧化钙负载量为0.67 mmol/g就能覆盖活性白土的酸活性中心,然后在80℃、4倍水中,加入17 mmol NaOH/g土,氢氧化钠加入速度为1.11 mmol/min时,得到氢氧化钠负载量为3.4 mmol/g的固体碱催化剂。将该催化剂用于生物柴油酯交换反应,当催化剂用量为油脂质量的3%时,甲酯转化率超过97%,反应完成后生物柴油无需洗涤。