Influence of pulse-jet cleaning pressure on performance of compact dust collector with pleated filter operated in clean-on-time mode

To operate a bag filter continuously, pulse-jet cleaning of dust particles from the filter medium is commonly required, and the pulse-jet pressure significantly affects the filter performance. In this study, the accumulation structure of residual dust particles inside and on the surface of a filter medium at different pulse-jet pressures was investigated by constructing a simple model, and the influence of the dust structure on the filter performance was clarified. Using a simple model, we determined the effective ratio of filtration area β, which represents the ratio of the filterable area to the total filtration area, the true resistance coefficient due to the primary dust layer ζ_p’ thinly deposited on the filter surface, and the true resistance coefficient inside the filter media itself ζ_f’_. The effective ratio of filtration area β decreased with operation time for all pulse-jet pressures; however, it maintained a high value when the pulse-jet pressure was high. The validity of β analyzed by the model was verified using two different methods, and the results showed good agreement, indicating that the model is effective in identifying real conditions. The true resistance coefficient due to the primary dust layer ζ_p’ decreased as the pulse-jet pressure increased; however, the true resistance coefficient inside the filter media itself ζ_f’ was the highest at 0.5 MPa. In addition, the dust collection efficiency was different at each pulse-jet pressure, which was considered to be caused by the difference in the dust particle accumulation structure.     

大麻工艺纤维长度与细度的相关性初探

通过对大麻工艺纤维长度和直径投影宽度的相关性研究，认为大麻工艺纤维长度和细度之间存在“越长越粗，越短越细”的规律。     

传统机械加工表面形貌评定的缺陷及发展方向

本文通过对传统机械加工表面形貌评定体系的分析，指出其不能完整地、从本质上反映表面的特征。并提出轮廓长度率、表面真面积率、表面分形维数D、比例系数K四个评定参数，通过分析可以看出这组参数比传统方法所具有的优越性和代替传统方法的可能性。     

圆杆弹性和弹—塑性扭转公式的探讨

对圆杆在线弹性阶段，弹－塑性阶段和全塑性阶段的扭转剪应力的计算公式作了分析，并推导了在材料的应力－应变关系（τ－γ关系）不服从虎克定律时，扭转真实剪应力的计算公式。文中对扭转强度计算公式的来源，物理含义及其都作了详细的说明。这对执行和理解国家ＧＢ１０１２８－８８《金属室温扭转试验方法》是有益的，而且对高校中材料力学的教学具有一定的参考价值。     

Understanding of the tensile deformation in HDPE/LDPE blends based on their crystal structure and phase morphology

The mechanisms of tensile deformation in high density polyethylene/low density polyethylene (HDPE/LDPE) blends were studied by a video-controlled tensile set-up, combined with dynamic mechanical analysis and small angle X-ray scattering. When quenching from the melt to room temperature, HDPE forms well-organized spherulits with high crystallinity and rigid amorphous layers between lamellae, and LDPE forms irregular aggregates with low crystallinity and mobile amorphous layers between lamellae. A separate lamellar stack-like structure is formed in HDPE/LDPE blends during the quenching. The deformation is affected by both the crystal structure and the phase morphology. Because the semi-crystalline polymers are made up of two interpenetrating networks, one is built up by the entangled fluid part and the other by the crystallites, at low deformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows the system to maintain a homogeneous strain distribution in the sample. The assumption of a homogeneous strain distribution can now be further proved by the tensile deformation in HDPE/LDPE blends, which shows two-step processes, with HDPE crystallites being broken down first at imposed strain of 0.4 and then LDPE crystallites being broken later, at an imposed strain of 0.6.     

基于B-ISVM算法的物联网云存储数据伪装不良信息检测

针对物联网云存储数据伪装不良信息隐蔽性造成的信息量预处理困难、深层次语义理解不准确和样本不均衡等问题,提出了一种基于B-ISVM(Boundary-Incremental SVM)算法的物联网云存储数据不良信息检测算法。在该算法中,首先采取基于均值和标准差的K均值初始聚类分析对云存储数据信息量进行样本空间训练分类;然后将所有样本类进行欧氏距离遍历计算,得到类间子聚类中心距离矩阵和各聚类中心的邻界子聚类区;再通过信息量伪装与筛选原理进行云存储信息真伪筛选,以不良信息在伪信息中发生的概率为指数、以数据安全度阂值和不良伪装信息模板向量集的相似度阂值为指标,对云存储信息量进行识别;最后进行增量模式学习,得到各分类样本最终的最优分类超平面,并将各类检测出的不良伪装信息进行输出。系统测试证明,该算法能快速有效地对物联网云存储数据中的伪装信息进行检测。     

网络安全中随机数技术分析与应用

介绍随机数技术在网络安全软件中的重要意义,分析了当前多种随机数产生方法及特点和不足之处。在网络环境下利用真随机数产生方法实现了一种安全机制,并将其应用于某防火墙软件中,应用结果显示了所用方法的优越性。     

The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency

Water splitting will become important to store excess renewable electrical energy into hydrogen. Although the oxygen-evolution reaction (OER) by water oxidation is a critical reaction for water splitting, further investigations are needed to find the details of the OER mechanism for various electrocatalysts. More in particular for homogeneous electrocatalysts, the Randles-Sevcik equation has been extensively applied to determine the turnover frequency (TOF). Herein, using vitamin B₁₂ as a case study, we show that the dynamical deposition/dissolution of the heterogeneous catalyst during OER makes the Randles-Sevcik equation too complicated to be used for calculating the TOF. Indeed, the conventionally applied post-characterization methods do not provide sufficient accuracy to prove the homogeneity of OER mechanisms; thus, using the Randles-Sevcik equation to calculate the TOF is not necessarily correct.     

A tetranuclear nickel(II) complex for water oxidation: Meeting new challenges

Ni complexes are promising catalysts for water splitting. Herein, a tetranuclear nickel(II) complex with bis-[(E)-N′-(1-(pyridin-2-yl)ethylidene)]carbohydrazide (HL), was synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. The complex is a tetranuclear complex and the ligands are coordinated to the metal ions in the mono-negative form, (L)^- to form a tetranuclear [NiL]₄⁴⁺ unit. Each Ni(II) ion is six-coordinated by pyridine nitrogen, azomethine nitrogen and oxygen atoms of two perpendicular carbohydrazone ligands in the mer configuration. The complex was studied as a water-oxidizing catalyst. In the next step, the role of the Ni-based compound for water oxidation on the surface of fluorine doped tin oxide as one of the true catalysts was investigated by scanning transmission electron microscopy, scanning transmission electron microscopy, spectroelectrochemistry, and electrochemistry. The electrode after water oxidation by the complex was studied and a relation between the decomposition of the Ni complex and water-oxidation reaction was proposed. The experiments show that under water-oxidation condition in the presence of the complex, a Ni-based compound on the electrode is a candidate as a contributor to the observed catalysis.