Effects of natural forest conversion and plantation tree species composition on soil macrofauna communities in Northeast China mountains

As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.

Uncovering the solid-phase conversion mechanism via a new range of organosulfur polymer composite cathodes for lithium-sulfur batteries

The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both cycle life and energy density.To realize an ideal solid-phase conversion of sulfur,a deep understanding of the regulation path of reaction mechanism and a corresponding intentional material and/or cathode design are highly essential.Herein,via covalently fixing of sulfur onto the triallyl isocyanurate,a series of S-triallyl isocyanurate organosulfur polymer composites(STIs) are developed.Relationship between the structure and the electrochemical conversion behavior of STIs is systematically investigated.It is found that the structure of STIs varies with the synthetic temperature,and correspondingly the electrochemical redox of sulfur can be controlled from conventional "solid-liquid-solid" conversion to the "solid-solid" one.Among the STI series,the STI-5 composite realizes an ideal solid-phase conversion and demonstrates great potential for building a Li-S battery with high-energy density and long-cyclelife:it realizes stable cycling over 1000 cycles in carbonate electrolyte,with a degradation rate of0.053% per cycle;the corresponding pouch cell shows almost no capacity decay for 125 cycles under the conditions of high sulfur loading(4.5 mg cm^(-2)) and lean electrolyte(8 μL mg_s^(-1)).In addition,the tailoring strategy of STI can also apply to other precursors with allyl functional groups to develop new organosulfur polymers for "solid-solid" sulfur cathodes.The vulcanized triallyl phosphate(STP) and triallylamine(STA) both show great lithium storage potential.This strategy successfully develops a new family of organosulfur polymers as cathodes for Li-S batteries via solid-phase conversion of sulfur,and brings insights to the mechanism study in Li-S batteries.

Rational design of natural leather-based water evaporator for electricity generation and functional applications

In recent years,water evaporation-induced electricity has attracted a great deal of attention as an emerging green and renewable energy harvesting technology.Although abundant materials have been developed to fabricate hydrovoltaic devices,the limitations of high costs,inconvenient storage and transport,low environmental benefits,and unadaptable shape have restricted their wide applications.Here,an electricity generator driven by water evaporation has been engineered based on natural biomass leather with inherent properties of good moisture permeability,excellent wettability,physicochemical stability,flexibility,and biocompatibility.Including numerous nano/microchannels together with rich oxygen-bearing functional groups,the natural leather-based water evaporator,Leather_(Emblic-NPs-SA/CB),could continuously produce electricity even staying outside,achieving a maximum output voltage of∼3 V with six-series connection.Furthermore,the leather-based water evaporator has enormous potential for use as a flexible self-powered electronic floor and seawater demineralizer due to its sensitive pressure sensing ability as well as its excellent photothermal conversion efficiency(96.3%)and thus fast water evaporation rate(2.65 kg m^(−2)h^(−1)).This work offers a new and functional material for the construction of hydrovoltaic devices to harvest the sustained green energy from water evaporation in arbitrary ambient environments,which shows great promise in their widespread applications.

Electrospinning-derived functional carbon-based materials for energy conversion and storage

The over-exploitation of fossil fuel energy has brought about serious environmental problems.It would be of great significance to construct efficient energy conversion and storage system to maximize utilize renewable energy,which contributes to reducing environmental hazards.For the past few years,in terms of electrocatalysis and energy storage,carbon fiber materials show great advantages due to its outstanding electrical conductivity,good flexibility and mechanical property.As a simple and low-cost technique,electrospinning can be employed to prepare various nanofibers.It is noted that the functional fiber materials with different special structure and composition can be obtained for energy conversion and storage by combining electrospinning with other post-processing.In this paper,the structural design,controllable synthesis and multifunctional applications of electrospinning-derived functional carbon-based materials(EFCMs)is reviewed.Firstly,we briefly introduce the history,basic principle and typical equipment of electrospinning.Then we discuss the strategies for preparing EFCMs with different structures and composition in detail.In addition,we show recently the application of advanced EFCMs in energy conversion and storage,such as nitrogen species reduction reaction,CO_(2) reduction reaction,oxygen reduction reaction,water-splitting,supercapacitors and ion batteries.In the end,we propose some perspectives on the future development direction of EFCMs.

Elucidating the dominant reaction mechanism of methanol-to-olefins conversion in H-SAPO-18: A first-principles study

The reaction mechanism of zeolite- or zeotype-catalyzed methanol-to-olefins（MTO） conversion is still a subject of debate. Employing periodic density functional theory calculations, the olefin-based cycle was studied using tetramethylethene（TME） as a representative olefinic hydrocarbon pool in H-SAPO-18 zeotype. The overall free energy barrier at 673 K was calculated and found to be less than 150 kJ/mol in the TME-based cycle, much lower than those in the aromatic-based cycle（〉 200 kJ/mol）, indicating that olefins themselves are the dominant active hydrocarbon pool species in H-SAPO-18. The similarity of the intermediates involved between the aromatic-based cycle and the olefin-based cycle was also highlighted, revealing that both cycles were pattern-consistent. The selectivity related to the distribution of cracking precursors, such as higher olefins or carbenium ions, as a result of the olefin-based cycle for the MTO conversion. The enthalpy barrier of the crack-ing step scaled linearly with the number of carbon atoms of cracking precursors to produce ethene or propene with ethene being much less favored than propene for cracking of C7 and higher pre-cursors. This work highlighted the importance of the olefin-based cycle in H-SAPO-18 for the MTO conversion and established the similarity between the olefin-based and aromatic-based cycles.

Reflection on Teaching Language from Analysis of Interpersonal Function in Cross-cultural Conversations

The interpersonal function in Halliday's system-functional grammar can instruct and apply to many-sided language communication.The article is aimed at analyzing language function reflected in the conversations between international students in different cultural background and native speakers,and then getting reflections on classroom teaching language.

Conversion Margins for the Major Uses of Agricultural Land and Their Variations in Shandong Province, China

It is of practical significance for the decision-making on country food security and farmland protection to analyze the conversion margins for the major uses of agricultural land and their variations. Based on the panel data of wheat, corn, vegetable, fruit, and forests productions from 520 investigated farmer households of 13 investigated villages in Shandong Province from 2003 to 2009, and using Cobb-Douglas production function, the revenue conversion margins can be obtained separately, between different grain-crops （wheat, corn） and different non-grain crops （vegetable, fruit, forests）, and the conversion relationship between growing grain（ wheat, corn） and going out for non-farm work. The results show that from 2003 to 2009, growing wheat and corn are more economically and reasonably for farmers, compared with growing vegetable, but growing wheat and corn are becoming less economically and less reasonably day by day, compared with planting forests. Moreover, the conversion margin between wheat and fruit shows obvious scissors difference. Just from 2007, farm- ers＇ growing fruit became economically and reasonably, but until 2009, compared with going out to work after abandoning farm- land, growing wheat had no economic rationality. From 2003 to 2009, farmers＇ growing corn is more profitable than growing fruit and going out for non-farm work after abandoning farmland. The subsidies for wheat and corn have increased farmers＇ comparative income from food production remarkably, but the subsidies cannot change the general tendency that farmers transform food （wheat, corn） production into non-food （especially forests） production. The revenue difference between growing wheat, corn and vegetable and growing fruit and forests is being pulled ceaselessly bigger, and the tendency that farmers transform wheat, corn and vegetable growing lands into fruit and forests growing lands has become increasingly apparent.

Welfare Balance of Different Interest Groups During Rural-urban Land Conversion

Rural-urban land conversion is currently a common social economic phenomenon during the process of economic development and rural urbanization in China. Rural-urban land conversion is positively effective as far as social and economic benefits are concerned (Yang, 2002), but its negative effect is also evident, resulting in such problems as low efficiency of rural land configuration and loss of social welfare. Consequently, farm-ers should also have an equal chance to enjoy the social welfare enhanced by land conversion. Based on the theories of welfare economy, this paper puts forward policy suggestions by discussing the welfare changes of various interest groups, builds the model of welfare distribution, and analyzes the conditions of maximizing social welfare. The absolute and opposite value of social welfare is closely related with the speed of rural-urban land conversion, and governments should give farmers and collectives fair compensa-tion to make up for the utility loss caused by land expropriation, which are conclusions drawn from this paper. This study aims to provide a theoretical basis for regulating targets and evaluation criteria, realizing the mechanism and implementation of public po-lices during rural-urban land conversion.

The Communicative Functions of Intentional isinterpretation in Daily Conversation

The present study analyzes the phenomenon of intentional misinterpretation in verbal communication and its communicative functions. In human verbal communication, misunderstanding occurs when the hearer’s understanding of the speaker’s utterances is not identical with the speaker’s intended one. However, in some cases, the hearer may intentionally choose the interpretation diverging from the speaker’s intended meaning in order to achieve certain communicative effects. This kind of linguistic phenomenon can be called intentional misinterpretation, which performs various functions in human daily conversation.

Interpersonal Functions of Doctor-Patient Conversations

As an indispensable part of medical practice.doctor-patient conversation is drawing more and more attention in the field of sociology,psychology and linguistics.Little attention,however,has been paid to the interpersonal aspect of the conversation between doctors and patients,which is regarded as one of the most complex interpersonal relationships.Being dominant in the interaction,doctors'words,mainly in the form of questions,deserve more studies,especially for the interpersonal functions delivered.This study mainly focuses on this aspect.

Adaptive Fuzzy Sliding Mode Controller for Grid Interface Ocean Wave Energy Conversion

This paper presents a closed-loop vector control structure based on adaptive Fuzzy Logic Sliding Mode Controller (FL-SMC) for a grid-connected Wave Energy Conversion System (WECS) driven Self-Excited Induction Generator (SEIG). The aim of the developed control method is to automatically tune and optimize the scaling factors and the membership functions of the Fuzzy Logic Controllers (FLC) using Multi-Objective Genetic Algorithms (MOGA) and Multi-Objective Particle Swarm Optimization (MOPSO). Two Pulse Width Modulated voltage source PWM converters with a carrier-based Sinusoidal PWM modulation for both Generator- and Grid-side converters have been connected back to back between the generator terminals and utility grid via common DC link. The indirect vector control scheme is implemented to maintain balance between generated power and power supplied to the grid and maintain the terminal voltage of the generator and the DC bus voltage constant for variable rotor speed and load. Simulation study has been carried out using the MATLAB/Simulink environment to verify the robustness of the power electronics converters and the effectiveness of proposed control method under steady state and transient conditions and also machine parameters mismatches. The proposed control scheme has improved the voltage regulation and the transient performance of the wave energy scheme over a wide range of operating conditions.

An Analysis on Functions of Interruptions in Specific Conversational Situations

The functional analysis of interruption is of great necessity in carrying out a smooth conversation.By exemplifying interruptions in specific conversational situations identified in Friends,the paper has explored the relative,interactive,pluralistic and situational characteristics of functions of interruptions.

建筑空间最优节能设计模型仿真研究

由于建筑结构主体较多,空间能耗难以合并控制,导致目前建筑空间能源耗用量较大。为此,构建基于等效转换法的建筑空间最优节能模型,并对其仿真研究。提出建筑总体能耗作为初始优化的“尺度”概念,该尺度为建筑空间的外墙、内墙、屋顶、分户楼板以及门窗等参数,求解这些尺度的最佳标准值。采用等效转换法计算在节能条件下所能接受的最大能耗范围。在此基础上,以上述范围值为约束条件,建立控制函数。将上述提到标准尺度值和最大能耗范围设置为最优解,建立最优节能设计模型,设定温差调节因子,对每一次室内外温差实施有效调节控制,保证建筑体参数符合最佳能耗范围。仿真结果证明,所提方法对冬季采暖和夏季制冷的能耗控制效果均较佳,节能效果最优且算法收敛性高,鲁棒性较好。

太赫兹各向异性超材料极化调控器设计与实现

电磁波极化特性会影响无线通信系统的性能,随着电磁场与微波技术的广泛应用,为满足信息传输和信息获取需求,电磁波极化特性的自由调控变得非常重要,在无线通信和雷达目标识别技术领域,都是通过改变极化状态来实现极化自由调控,随着波长的变短,相比微波通信,太赫兹通信具备频谱资源更丰富、传输速率更高的优势,但传统结构的极化调控器因存在各种缺陷,在太赫兹频段中的应用具有一定的局限性。针对这个问题,利用各向异性超材料设计了一款可用于太赫兹频段的双功能极化调控器,首先采用坐标分解法分析了器件的双功能极化调控特性,分析结果表明所设计的调控器既可以实现线极化波调控,又可以实现圆极化波调控,具备双功能调控特点;然后采用表面电流法分析了调控器的极化转换机理,仿真结果表明调控器具有4个谐振点,超材料单元结构中发生的四阶电磁谐振叠加,使得调控器工作频带宽,且极化转化效率高,在0.45~1.152 THz的频带内效率可高达90%以上;最后还分析了器件的不同参数对器件性能的影响,提出了调控器性能的优化思路和调控器的实际使用条件。通过对结构参数的分析,发现结构参数的变化会影响调控器工作时的频带宽度和谐振点的分布位置,调控器性能与自身工作频带宽度存在互斥关系,工作频带变宽,调控器性能变差,工作频带变窄,调控器性能变好,在调控器的实际应用过程中,为获取满意的调控特性,要根据具体的调控要求对结构参数进行优化调整;通过对入射角和方位角的分析,发现调控器性能对入射角的变化非常敏感,并指出在使用调控器时,它的摆放位置方向要满足入射波在调控器中的投影与调控器边沿保持平行。与现有工作相比,所设计的调控器性能更高效,结构更简单,并且双功能特性使器件的使用更加便捷和多样化,该工作为太赫兹极化转化器的发展和应用提供了理论参考。

Er掺杂PbF_(2)晶体的局域团簇结构与光谱性能研究

本文采用Bridgman法成功生长了一系列Er∶PbF_(2)晶体。利用基于密度泛函理论的第一性原理计算详细研究了Er^(3+)在PbF_(2)晶体中的团簇效应。首次获得了Er∶PbF_(2)晶体的上转换发光特性(发光强度、颜色变化)与团簇结构之间的关系。研究发现,随着Er^(3+)浓度增加,团簇从单聚体向高阶构型演化,Er^(3+)离子之间的距离先减小后增大,这使得上转换发光中的红色发射强度先增大后减小,红绿发光比也在Er^(3+)浓度高于6.5%(摩尔分数)后逐渐减小,即发光颜色可以从红色调整为黄绿色。该研究证明了稀土离子团簇的结构演化可以调控Er∶PbF_(2)的光谱特性,为多色发光材料的设计提供一种新方法。

多功能海军导弹运输车技术研究

针对海军舰载导弹转运及装舰过程中,运输车功能单一、通用性差,且装舰操作流程繁琐、时间长的问题,提出一种多功能导弹运输车的技术方案,该方案以通用化和结构功能一体化为设计理念,对运输车的运输功能与辅助起竖功能进行一体化设计,在满足海通各型导弹公路运输功能的前提下,集成导弹水平、垂直姿态转换的功能,突破筒弹在舰面装填方式的限制,解决筒弹装舰过程中吊装流程繁琐的问题,实现在运输车上直接起竖筒弹的功能,缩短筒弹装舰时间。该方案使得舰载导弹转运、装舰的流程得以简化,提升了装备的使用效能。

基于传递函数分析的双馈风力发电系统动态建模方法研究

以双馈风力发电系统(doubly-fed induction generator based wind energy conversion system,DFIG-based WECS)为例,利用小信号分析法推导出由风机、双质量块传动链构成的动力与传动系统通用传递函数方程。动力与传动系统传递函数的零极点位置、稳定性与系统参数及系统运行工作点相关。该传递函数可进一步分解为扭转分量和非扭转分量。传动链参数仅对扭转分量造成影响。在此基础上,建立了考虑动力传动、电机、变流器、控制等环节的风力发电系统传递函数模型。模型综合了各环节参数,可直观反映系统参数对系统响应的影响,有助于深入了解系统动态行为。算例及时域仿真结果证明了所提出传递函数模型的准确性和高效性,可为系统参数设计研究提供理论依据。

属性权重动态更新的自适应群体共识决策方法

为了提高不确定语言环境下异构多属性群决策的质量、效率及可解释性,提出一种属性权重动态更新的自适应群体共识决策方法。首先,定义不确定语言变量与中间值之间的转换函数,发展多级共识测度,建立计算属性初始权重的双目标优化模型;进而,构建包含群体共识自动达成规则和属性权重动态更新机制的自适应共识模型,实现待调整值的精准定位和自动修改,在优化属性权重的同时进一步提升群体共识水平;然后,对于达成共识的群体决策矩阵,先利用转换函数将中间值转换为不确定语言变量,再使用属性权重和集结算子得到各方案的综合评价结果;最后,通过供应商选择实例和实验比较分析验证所提方法的有效性和可行性。本文研究结果为灵活、高效地求解复杂环境下的多属性群决策问题提供了有效途径。

吐鲁番市土地利用转型及生态服务功能交叉敏感性

厘清吐鲁番市2000-2018年土地利用转型及生态服务价值时空演变特征,探讨生态服务价值与地类转型的相互关系,可为合理规划区域土地资源的同时实现生态服务功能的改善和提升提供依据。基于5期土地利用遥感影像数据,采用土地利用动态变化模型及修正后的生态服务价值系数,结合改进的交叉敏感性系数模型分析生态服务价值对土地利用转型的敏感程度。结果表明,1)吐鲁番市以草地、未利用地及耕地等地类为主,建设用地、耕地持续扩张,水域、草地不断减少,其中以草地与水域、耕地及未利用地之间的转型为主;2)研究时段内生态系统服务价值呈现“先减后增再减”的动态变化趋势,高值区主要分布于北部山区以及中部绿洲平原区域;3)生态服务功能对林地、水域、草地及未利用地向其他地类转型敏感性响应程度较高,草地、建设用地与未利用地转型的高敏感区分布较广,未利用地与水域、建设用地间转型的低敏感区分布较广。区域应加强对水域、林地、草地等生态系统的保护,在发展经济建设的同时注重合理规划土地资源及生态环境质量的提升。

大型硫回收装置多功能CO变换加氢催化剂应用总结

普光气田是国内成功开发的首个高含硫气田,原料气(天然气)碳硫比高,再生酸性气CO_(2)含量高,会反应生成CO继而生成COS、CS_(2)等有机物,成为影响装置达标排放的关键因素之一。研究开发了具有CO变换功能的克劳斯尾气加氢催化剂,并成功应用于中国石化中原油田普光气田天然气净化厂200 kt/a硫回收装置。工业应用结果表明:加氢反应器过程气CO变换率超过90%,在线炉制氢天然气消耗量减少279 m^(3)/h,催化剂加氢转化率、有机硫水解率均超过99%,烟气SO_(2)排放浓度降至200 mg/m^(3)以下,CO排放浓度降低了90%,效益显著。