Economic effects of regulating the seismic strengthening of older buildings

The marked increase in the awareness of earthquake risk following the Canterbury earthquakes in New Zealand offered a unique opportunity to investigate the economic effect of disaster-mitigation regulations on the commercial building stock. A difference-in-differences (DD) framework was used to determine whether earthquake risk has been capitalized into the property prices of buildings constructed prior to 1976, as a response to the national policy requiring assessment and strengthening (or demolition) of the existing earthquake-prone building stock. A negative externality is found in the policy announcement on affected (pre-1970s) office and retail buildings which caused office buildings to suffer a 12.5% stigma discount. However, retail properties were less impacted suffering a 2.3% stigma loss. The value of the commercial building stock has been affected by the policy. These findings provide policy-makers with timely evidence as to the economic effects of New Zealand’s earthquake-prone buildings policy. Facing losses in property value and financial responsibility for retrofitting their assets, building owners will be looking for a workable set of regulatory and non-regulatory incentives to encourage disaster risk management and protect the built environment.     

基于区块链技术的公益时间银行系统

在现有的时间银行系统中，时间币的发行功能和结算功能完全集中到一个中心节点上。这种极度中心化的功能结构，不仅存在容易发生中心节点单点失效、数据容易被篡改等信息安全问题，还存在着时间币的发行和流通缺乏透明度以及时间币的结算依赖中心化的结算机构等问题。针对这些问题，提出了一种基于区块链技术的解决方法。首先，将时间币的发行功能和结算功能从中心节点上分离出来；然后，利用具有分布式去中心化、集体维护和不可篡改等特性的区块链技术，将分离出来的发行功能逐步去中心化，将分离出来的结算功能去中心化，形成公益时间链（PWTB）；最终，PWTB利用区块链技术以去中心化的方式将时间银行系统由单个节点维护账本变成由集体维护一个分布式的共享账本，使时间币的发行和流通公开透明，时间币的结算不依赖某个中心化的节点。安全分析表明所设计的PWTB能够实现安全的信息传输与存储，以及数据的共享。     

Flow control with electrode bank arrangements by electrohydrodynamics force for heat transfer enhancement in a porous medium

Active flow control with electrohydrodynamics (EHD) force in the channel flow has been numerically investigated for enhancing heat transfer. This study focuses on the effect of electrode bank arrangements and the number of electrodes on corona wind and fluid flow for heat transfer onto a porous medium. Aligned and staggered configurations of electrode banks are compared. The numerical results show that electric field intensity depends on electrical voltage and the number of electrodes. Shear flow is increased with larger numbers of electrodes and in the aligned configuration, resulting in the enhancement of vortex strength. The swirling flow from staggered configurations spread wider than that of aligned configurations, but the aligned configuration produced more turbulence. In addition, the temperature distribution in the channel flow is increased with increasing numbers of electrodes. With the effect of swirling flow, airflow above the porous sample surface is faster leads the heat to more transfer to the porous sample surface. This causes the temperature of porous medium to increase rapidly so the convective heat transfer coefficient on porous medium surface is increased. Finally, the modified case of the numerical results is validated against the experimental results. The experimental flow visualization is based on the incense smoke technique, in order to verify the accuracy of the swirling flow pattern subjected to the electric field. It is shown that the comparison results in both techniques are in good agreement.     

当雄牦牛肉的营养和风味特性

以市售西门塔尔牛肉（下文简称“市售牛肉”）作为对照组，研究当雄牦牛肉的营养和风味特性。采用高效液相色谱、气相色谱-质谱联用、凯氏定氮等方法分别分析当雄牦牛肉和市售牛肉中蛋白质、氨基酸、脂肪酸、挥发性风味物质、矿物质和维生素差异。结果表明：当雄牦牛肉中蛋白质含量（22.89 g/100 g）显著高于市售牛肉（P＜0.05），剪切力及蒸煮损失率显著低于市售牛肉（P＜0.05）；当雄牦牛肉中VB1、VE含量显著高于市售牛肉（P＜0.05），2 种牛肉中的VB2、VA含量无显著差异；当雄牦牛肉中总氨基酸、必需氨基酸、总脂肪酸及不饱和脂肪酸含量均显著高于市售牛肉（P＜0.05）；微量元素分析结果发现，当雄牦牛肉中锰、硒、镁、铁、钙元素的含量均显著高于市售牛肉（P＜0.05）；当雄牦牛肉及市售牛肉中分别检测出58、43 种挥发性风味物质，牦牛肉中醇类和酯类的种类及含量均高于市售牛肉，而市售牛肉中酚类、醛类、酮类及含氮化合物的含量均较高。因此，当雄牦牛肉具有较好的食用营养品质。     

基于改进词嵌入表示和卷积神经网络的银行智能派单系统的研究

银行智能派单系统的实现和功能完善,对银行提升客户满意度、提高突发事件处理效率、降低人工处理成本等非常重要。针对现有的基于Word2vec和TextCNN模型的银行智能派单系统进行了改进,针对特征词权重表达性弱,特征词类别及位置区分性弱等问题,提出基于改进TF-IDF加权的Word2vec词嵌入表示和卷积神经网络结合的银行智能派单系统:首先利用Word2vec模型得到输入事件单的词嵌入向量;再针对经典TF-IDF方法不具备类别区分性、位置区分性,也没有考虑极端频率特征词代表性的情况,提出改进型TF-IDF算法,计算每个特征词的权重,得到基于改进TF-IDF加权的Word2vec词嵌入表示;最后在卷积神经网络模型中进行训练,通过迭代训练最终得到分类器,利用分类器可对输入事件单信息自动进行系统类别的判断。实验结果表明改进词嵌入表示的银行智能派单系统分类模型的宏查准率、宏查全率、准确率以及宏F1值都得到进一步的提高。     

Loss cost reduction and power quality improvement with applying robust optimization algorithm for optimum energy storage system placement and capacitor bank allocation

Power losses cause the underutilization of distributed generation (DG) units in addition to the cost increasing in microgrid. Minimizing these losses has been focused in many papers. Using energy storage system (ESS) is a crucial solution for loss reduction. ESS can balance the power exchange in on-peak times where its location and size optimization can improve the microgrid efficiency and reduce the loss cost significantly. Moreover, to ensure the power quality by improving the voltage profile, capacitor bank can be installed optimally on some buses. Optimization of size and location of the capacitor bank can enhance the reactive power that is leading to power loss reduction. In other words, the capacitor bank is applied to compensate the total reactive power and consequently, the current is reduced that results in power loss reduction. In this article, the problem is defined as the optimum location and size of ESS and capacitor bank in the microgrid. Due to the complexity of the problem in many options for selecting the buses to implement these elements (ESS and capacitor bank), robust approach using the particle swarm optimization algorithm and general algebraic modeling system are applied for optimization process. In addition, the uncertainty of renewable DGs such as photovoltaic and wind turbine is modeled by probability density functions and Monte-Carlo is used for selecting more probable cases in optimization processes. The results show the loss cost reduction and improvement in voltage and power profile with less fluctuations and more stability.     

基于SARIMA-GRNN-SVM的短期商业电力负荷组合预测方法

针对短期商业电力负荷预测准确性与周期难以满足现有电力现货市场的问题,提出了一种基于SARIMAGRNN-SVM(seasonal autoregressive integrated moving average-generalized regression neural network-support vector machine)的商业电力负荷组合预测模型。首先,对商业电力负荷变化的周期规律与随机因素的复杂影响进行了分析;然后,结合以上分析,选用SARIMA和GRNN为单一预测模型对商业电力负荷进行预测,并利用SVM进行组合,实现日前商业电力负荷预测;最后,通过某商业综合体的电力负荷数据进行验证。所提组合预测模型较单一预测模型拥有更优的预测精度与鲁棒性,可以为短期商业电力负荷预测提供借鉴。     

Design of two-channel filter bank using nature inspired optimization based fractional derivative constraints

In this article, a novel approach for 2-channel linear phase quadrature mirror filter (QMF) bank design based on a hybrid of gradient based optimization and optimization of fractional derivative constraints is introduced. For the purpose of this work, recently proposed nature inspired optimization techniques such as cuckoo search (CS), modified cuckoo search (MCS) and wind driven optimization (WDO) are explored for the design of QMF bank. 2-Channel QMF is also designed with particle swarm optimization (PSO) and artificial bee colony (ABC) nature inspired optimization techniques. The design problem is formulated in frequency domain as sum of L₂ norm of error in passband, stopband and transition band at quadrature frequency. The contribution of this work is the novel hybrid combination of gradient based optimization (Lagrange multiplier method) and nature inspired optimization (CS, MCS, WDO, PSO and ABC) and its usage for optimizing the design problem. Performance of the proposed method is evaluated by passband error (ϕ_p), stopband error (ϕ_s), transition band error (ϕ_t), peak reconstruction error (PRE), stopband attenuation (A_s) and computational time. The design examples illustrate the ingenuity of the proposed method. Results are also compared with the other existing algorithms, and it was found that the proposed method gives best result in terms of peak reconstruction error and transition band error while it is comparable in terms of passband and stopband error. Results show that the proposed method is successful for both lower and higher order 2-channel QMF bank design. A comparative study of various nature inspired optimization techniques is also presented, and the study singles out CS as a best QMF optimization technique.     

中国商用车领域的铂族金属需求依然强劲

2020年以来中国商用车市场发生了很多变化，近期卡车销量从疫情萧条中大幅反弹，物流、基建以及排放标准升级共同推动了2020年商用车市场需求，对铂族金属的需求更加有利，对铂金需求的预期增长似乎比对钯金需求更有保障。     

MDCK细胞库的建立、检定及其生物学特性

目的建立MDCK细胞的主细胞库及工作细胞库,并进行检定,同时评价其生物学特性。方法从欧洲细胞保藏中心(European Collection of Authenticated Cell Culture,ECACC)引进1株MDCK细胞,经传代扩大培养后,分别建立主库及工作细胞库。按照《中国药典》三部(2015版)规定的方法对细胞库进行细胞活力、细胞形态、无菌、支原体及细胞内外源病毒因子检查,并对细胞生长状况、传代稳定性、流感病毒敏感性进行检测。结果建立的MDCK细胞主种子库及工作种子库细胞形态呈不规则的上皮样细胞状,生长状态良好,细胞活率分别为96.0%和95.5%,无菌、支原体及细胞内外源病毒因子检查结果均合格。MDCK细胞生长曲线均呈S型,培养48~96 h进入对数生长期,随后进入平台期。连续传10代48 h细胞活率在93.0%~95.5%之间,较稳定。MDCK细胞对流感病毒较敏感,对B型流感病毒的敏感性高于A型流感病毒。结论建立的主细胞库及工作细胞库各项检测结果均符合《中国药典》规定,具有良好的传代稳定性及流感病毒敏感性。