Comparative Studies on the Fine Structure and Elemental Composition of Envelopes of Trachelomonas and Strombomonas (Euglenophyta)

Fine structure and elemental composition of envelopes of 10 taxa of Trachelomonas and Strombomonas from natural freshwater bodies in China were studied and phylogeny of both genera were discussed. The results indicate that iron (Fe) and silicon (Si) are the primary mineral elements of the envelopes. Composition of mineral elements was uncorrelated with envelope color, however, it was highly correlated with the microarchitecture of the envelopes. Content of Si was higher than that of Fe in all species of Strombomonas and some species of Trachelomonas with rough surface. In most species of Trachelomonas, especially those with dense and smoothy surface, content of Fe was higher than that of Si. Based on the above results, we propose to assign those species of Strombomonas into Trachelomonas and consider them as a group of the latter. These species were the most primitive among the group with envelopes in Euglenaceae.

Structure simulation in unidirectionally solidified turbine blade by dendrite envelope tracking model(I):numerical modeling

A 3D dendrite envelope tracking model was developed for estimating the solidification structure of unidirectionally solidified turbine blade. The normal vector of dendrite envelope was estimated by the gradient of dendrite volume fraction, and growth velocity of the dendrite envelope (dendrite tips) was calculated with considering the anisotropy of grain growth. The solute redistribution at dendrite envelope was calculated by introducing an effective solute partition coefficient(ke). Simulation results show that the solute-build-up due to the rejection at envelope affects grain competition and consequently the solidification structure. The lower value of ke leads to more waved dendrite growth front and higher solute rejection. The model was applied to predict the structure of turbine-blade-shape samples showing good ability to reproduce the columnar and single grain structures.

Research on Evaluation and Optimization of Regional Land Use Structure Efficiency

[Objective] The purpose of this study is to judge the rationality of land use structure from new perspectives and method. [Method] The theory of data en- velopment analysis （DEA） has been employed in this article. A case study of evalu- ation of land use structure for Wujin district in 2012 is provided to illustrate the ap- plication of this research model. At the micro perspective, land use efficiency has been analyzed by use of data envelopment analysis model. The optimization and adjustment direction in land use structure has been pointed out from the view point of land use efficiency. [Result] The result has shown that the research method based on information entropy and data envelopment analysis model can effectively overcome the drawback of traditional evaluation techniques. Compared with the tra- ditional methods, the new optimization model based on a structure of the multi-crite- ria factors and objective weighting method can evaluate the rationality of land use structure more comprehensively.

Joint Estimation of Carrier Frequency and Phase Offset Based on Pilot Symbols in Quasi-Constant Envelope OFDM Satellite Systems

Spectral efficiency and energy efficiency are two important performance indicators of satellite systems. The Quasi-Constant Envelope Orthogonal Frequency Division Multiplexing(QCE-OFDM) technique can achieve both high spectral efficiency and low peak-to-average power ratio(PAPR). Therefore, the QCE-OFDM technique is considered as a promising candidate multi-carrier technique for satellite systems. However, the Doppler effect will cause the carrier frequency offset(CFO), and the non-ideal oscillator will cause the carrier phase offset(CPO) in satellite systems. The CFO and CPO will further result in the bit-error-rate(BER) performance degradation. Hence, it is important to estimate and compensate the CFO and CPO. This paper analyzes the effects of both CFO and CPO in QCE-OFDM satellite systems. Furthermore, we propose a joint CFO and CPO estimation method based on the pilot symbols in the frequency domain. In addition, the optimal pilot symbol structure with different pilot overheads is designed according to the minimum Cramer-Rao bound(CRB) criterion. Simulation results show that the estimation accuracy of the proposed method is close to the CRB.

Characteristics of structural loess strength and preliminary framework for joint strength formula

The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress （ Kf line）, and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests： the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural loess comprehensively and reasonably, a joint strength formula for structural loess was established. This formula comprehensively considers tensile and shear properties. Studies have shown that the tensile strength exhibits a decreasing trend with increasing water content. When the water content is constant, the tensile strength of the structurally intact soil is greater than that ofremolded soil. In the studies, no loss of the originally cured cohesion in the structurally intact soil samples was observed, given that the soil samples did not experience loading disturbance during the uniaxial compressive strength test, meaning there is a high initial structural strength. The results of the conventional triaxial shear strength test show that the water content is correlated with the strength of the structural loess. When the water content is low, the structural properties are strong, and when the water content is high, the structural properties are weak, which means that the water content and the ambient pressure have significant effects on the stress-strain relationship of structural loess. The established joint strength formula of structural loess effectively avoids overestimating the role of soil tensile strength in the traditional theory of Mohr-Coulomb strength.

Modelling envelope and temporal fine structure components of frequency-following responses in rat inferior colliculus

In studies of auditory perception, a dichotomy between envelope and temporal fine structure(TFS) has been emphasized. It has been shown that frequency-following responses(FFRs) in the rat inferior colliculus can be divided into the envelope component(FFREnv)and the temporal fine structure component(FFRTFS). However, the existing FFR models cannot successfully separate FFREnv and FFRTFS. This study was to develop a new FFR model to effectively distinguish FFREnv from FFRTFS by both combining the advantages of the two existing FFR models and simultaneously adding cellular properties of inferior colliculus neurons. To evaluate the validity of the present model, correlations between simulated FFRs and experimental data from the rat inferior colliculus were calculated. Different model parameters were tested, FFRs were calculated, and the parameters with highest prediction were chosen to establish an ideal FFR model. The results indicate that the new FFR model can provide reliable predictions for experimentally obtained FFREnv and FFRTFS.

基于包络学习和分级结构一致性机制的不平衡集成算法

集成方法是不平衡学习方法的重要分支,然而,现有不平衡集成方法均作用于原样本而没考虑样本的结构信息,因此其效能仍然有限.样本的结构信息包括局部和全局结构信息.为了解决上述问题,本文提出了一种基于深度样本包络网络(Deep Instance Envelope Network,DIEN)和分级结构一致性机制(Hierarchical Structure Consistency Mechanism,HSCM)的不平衡集成学习算法.该算法在考虑局部流形和全局结构信息的情况下,通过多层样本聚类,生成高质量的多层包络样本,从而实现类平衡化.首先,算法基于样本近邻拼接和模糊C均值聚类算法,设计DIEN来挖掘样本的结构信息,得到深度包络样本.然后,设计局部流形结构度量和全局结构分布度量来构建HSCM用于增强层间样本的分布一致性.接着,将DIEN和HSCM结合起来,构建出优化后的深度样本包络网络——DH(DIEN with HSCM).之后,将基分类器应用于包络样本.最后,设计bagging集成学习机制来融合基分类器的预测结果.文末组织了多组实验,采用了十多个公共数据集和有代表性的相关算法进行验证比较.实验结果表明,本文算法在AUC(Area Under Curve),F-measure等四个性能指标上显著最优.

相变储能材料在建筑围护结构领域的应用及研究进展

相变材料(PCM)具有结构稳定性好、高储能密度、可控相变温度、较大的相变潜热以及出色的储热能力,被用作建筑物中有效的潜在储能元件,以改善由温室气体排放引起的严重环境问题,可有效地减缓燃料和电能消耗,同时在建筑围护结构中保持舒适的环境,最大限度地减少温度波动。简述相变材料的分类及其选取,相变材料的封装工艺,重点介绍了相变储能材料在围护结构领域的研究与应用,指出了影响相变围护结构效率的因素,对其未来的研究方向进行了展望。

严寒地区农村住宅围护结构现状分析与优化研究

我国严寒地区气候寒冷且供暖季漫长,农村住宅采暖能耗问题突出,多数住宅采用自建形式,围护结构的热工性能普遍不理想。本研究从严寒地区农村住宅围护结构实际情况出发,对本溪农村地区200余户现有住宅进行调研。结果显示,本溪现有农宅基本未设置外墙保温,虽部分住宅屋顶设置保温,但保温材料均已超过使用年限,保温效果较差。有86.95%的农宅室内温度基本维持在18℃以下,农户满意度仅24.2%。实地测量3户典型农宅的室内环境温度。采用EnergyPlus模拟得到农宅围护结构的传热系数相比居住建筑节能设计标准规定限值超出300%~400%。根据实测数据和模拟数据对外墙、屋顶、外窗进行热工性能改造。对比单一围护结构改造前后的供暖季热负荷,得出外墙的改造效果最好。

内抹调湿砂浆外墙吸放湿特性及对负荷影响分析

本文从建筑围护结构节能出发,以内抹WSE(木质纤维Wood fibre、海泡石Sepio⁃lite、膨胀珍珠岩Expanded perlite)基复合调湿保温砂浆外墙为研究对象,将其与内抹普通砂浆外墙对比,分析吸放湿特性及其对负荷的影响.研究使用COMSOL Multiphysics有限元软件的建筑材料热湿耦合模型,分析环境湿度变化与外墙之间的湿迁移变化,以及与外墙的传热传质.以夏热冬冷典型气候地区长沙为例,分析内抹WSE基复合调湿保温砂浆外墙的负荷及潜热负荷占比,同时选取夏热冬暖地区广州和寒冷地区北京对比分析外墙的全年能耗.研究发现,内抹WSE基复合调湿保温砂浆外墙的吸放湿速率远大于内抹普通砂浆的外墙,并能长时间保持高速的吸放湿状态,同时比内抹普通砂浆墙体节省22.31%~23.85%的全年负荷.墙体在吸湿过程中,温升与吸湿速率能力体现出一致性,表明墙体内表面湿迁移对温度有着重要影响,并且湿迁移越大对温度影响越大.墙体在放湿过程中,温度迅速下降是放湿速率快的表现.内抹WSE基复合调湿保温砂浆墙体具有优良的吸放湿特性和节能潜力,可用于建筑围护结构节能.

农居建筑围护结构改造节能敏感性分析:以内蒙古河套地区为例

建筑节能问题是全社会普遍关注的焦点,农村建筑高能耗现状依然严峻。既有建筑节能多关注单一分类要素对能耗的量化影响,而不同组合要素对建筑热负荷影响的总体趋势、显著性和主次关系人们并不清楚。以内蒙河套地区农居为研究对象,通过正交实验、能耗模拟和多元回归方法,研究围护结构因素对建筑热性能的影响规律。结果显示:内蒙古河套地区建筑空间结构因素的主次顺序分别为阳光间进深>保温层厚度>透明围护结构>外墙结构>建筑朝向>窗墙比;当阳光间进深在1 m,保温70 mm,窗墙比为0.5时建筑热负荷最小;优化改造后,呼和浩特、包头、巴彦淖尔和鄂尔多斯的节能率分别为67.5%、69.2%、72.8%和76.5%,为分析空间围护结构因素量化规律和参数优选提供决策依据。

武汉东站枢纽地下换乘空间主体结构设计

武汉东站枢纽是集铁路、地铁、公交、出租、社会车辆等多种交通方式于一体的大型综合交通枢纽,其地下换乘空间包含国铁地下空间和2号线地铁站主体结构,并与站房地下通道、站前地下广场连通。文章结合武汉东站枢纽地下换乘空间建筑功能要求,分析了其主体结构设计,以保证地下换乘空间的安全性与合理性,可供类似地下结构设计参考。

建筑围护结构中辐射制冷材料与相变材料耦合应用的研究进展

随着全球气温上升和能源消耗增加,建筑节能技术的重要性日益凸显。辐射制冷材料(RCM)和相变材料(PCM)在建筑围护结构中的应用,为降低建筑能耗提供了有效途径。介绍了RCM与PCM的基本原理、分类及其在建筑围护结构中的耦合应用研究。研究表明,RCM与PCM耦合技术能够有效提升建筑物的隔热和储热性能,在夏季降温与冬季保温方面均优于单一材料的使用效果。然而,RCM与PCM的耦合技术在实际应用中仍面临气候适应性、居住舒适度、力学性能影响以及材料耐久性等挑战。未来的研究应综合考虑这些因素,以进一步优化该技术的实际应用潜力。

偏压受力车站围护结构变形规律分析

为了研究偏压受力车站围护结构在施工过程中的变形情况,以南宁市轨道交通5号线金桥站基坑工程为研究对象,采用PLAXIS软件对基坑开挖过程进行数值模拟,对比模拟计算结果与监测统计结果,研究基坑的变形规律。研究表明:偏压受力围护结构的内力及位移随着基坑开挖深度的加深而增大。在偏压荷载下,基坑两侧的地表竖向位移变形曲线呈凹槽形,主动压力侧地表沉降大于被动压力侧。第一道支撑轴力随开挖深度的增加而增大。受偏压荷载影响,基坑两侧桩体向被动压力侧发生整体偏移,主动压力侧桩体向基坑内侧偏移,变形曲线呈勺形。数值模拟结果与监测统计结果变化趋势相同,但数值偏小,对比分析表明数值模拟具有一定可靠性。

相变材料在围护结构中的应用及热工性能研究进展

在建筑围护结构中掺入相变材料能达到蓄放热、改善热工性能和节能目的。介绍了相变材料的分类、选择,求解相变传热过程方法。分析了围护结构与相变材料热工性能的相关性,热工性能受地区气候、室内环境、相变材料热物性、相变材料封装及应用方式等影响。通过相变砖、相变混凝土、相变砂浆和相变墙板等的应用,表明相变温度接近环境温度的算术平均值,相变材料封装面积、传热系数、潜热的增大,可有效地提高其热工性能和节能效果。研究相变围护结构的热工性能对建筑节能降碳具有重要意义。

新型轻质结构一体化外围护系统构造设计

针对国家对于新型装配式建筑“装饰一体化”的新要求,笔者研发设计了一种与装配式建筑相配套的,相对成熟的新型轻质结构一体化外围护系统,该系统兼顾良好的安全、保温隔热、防火、防水及隔声性能,实现了保温、装饰和结构功能的一体化集成,工厂化预制加工,现场装配式安装。本文简要介绍了该系统的设计理念,并进行了其标准板型和尺寸、建筑样板排版设计及主要原材料的选定。另外对其系统主要构造节点进行了优化设计,以确保选型的合理性及可靠性。

拉萨乡村民居围护结构热工性能优化研究

拉萨地区位于青藏高原太阳能富集区,冬季寒冷漫长、太阳辐射强烈且朝向差异大,当地乡村居住建筑冬季室内热环境差、能耗水平高。为提升该类建筑的室内热环境并兼顾节能环保,基于拉萨乡村民居现状建立典型建筑模型,选取各朝向围护结构的传热系数和热惰性指标共10项热工参数作为研究因素,采用不舒适度日数UCDD12和采暖期逐时累积热负荷作为热环境和节能效果的评价指标。设计正交试验并通过TRNSYS进行仿真模拟,研究了各热工参数对评价指标的影响规律、显著性程度和主次排序。结果表明,对UCDD12存在显著影响的热工参数有6项,由高到低排序为屋顶、北向、东/西向、南向传热系数及南向、东/西向热惰性指标;对累积热负荷存在显著影响的热工参数有7项,依次为屋顶、东/西向、北向、南向传热系数及南向、内墙、东/西向热惰性指标。进一步综合两项评价指标,使用TOPSIS法确定了各项热工参数的最佳组合方案。为改善拉萨乡村民居室内热环境、提升节能性能提供技术支持。

板壳结构在声振联合试验下的振动响应耦合分析

目的研究具有工程实践意义的板壳组合结构在声振联合作用下的响应预测方法。方法在噪声试验、振动试验和声振联合试验响应曲线的基础上,分析板壳组合结构在噪声和振动同时激励下的响应耦合规律,并根据噪声试验和振动试验的响应极值包络法,来预测在声振联合试验作用下板壳结构的响应分布。结果声振联合试验响应曲线近似于噪声试验和振动试验的最大值包络线,噪声的面激励和随机振动的基础激励在不同的频率范围内对结构响应起着主要影响。试验件的噪声试验和振动试验响应曲线在给定的频率点出现相交,小于交越频率的声振联合试验响应与振动试验高度吻合,高于交越频率的响应则以噪声试验为主。结论在工程实际中,可以直接利用振动试验和噪声试验的响应数据对声振联合试验的响应进行预测。由于交越频率难以事先获得,因此响应叠加法在实践中更易于实现。

轻钢房屋整体风致易损性分析

轻钢房屋被广泛用于民宅和厂房等低矮建筑中。该类结构轻质,对风荷载较为敏感,在台风中破坏严重,造成了巨大的经济损失,因此对该结构进行风灾评估具有重要意义。首先,基于随机模拟技术提出了轻钢房屋整体结构风致易损性的分析框架,其中涉及风荷载随机化方法、主体结构和围护结构风致易脆性分析方法以及房屋整体结构风致易损性分析流程。其次,基于所提框架对一具体轻钢结构风致易损性进行了案例分析,结果表明,所提方法较好考虑了飞掷物和风压联合作用及其造成的内压变化效应,并可将主体结构和围护结构的风灾损失进行融合,获得结构整体易损性曲线。

Strain transfer of surface-bonded fiber Bragg grating sensors for airship envelope structural health monitoring

This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.