Fuel-powered artificial muscles

Artificial muscles and electric motors found in autonomous robots and prosthetic limbs are typically battery-powered, which severely restricts the duration of their performance and can necessitate long inactivity during battery recharge. To help solve these problems, we demonstrated two types of artificial muscles that convert the chemical energy of high-energy-density fuels to mechanical energy. The first type stores electrical charge and uses changes in stored charge for mechanical actuation. In contrast with electrically powered electrochemical muscles, only half of the actuator cycle is electrochemical. The second type of fuel-powered muscle provides a demonstrated actuator stroke and power density comparable to those of natural skeletal muscle and generated stresses that are over a hundred times higher.     

一种新型振荡浮子式海洋波浪能发电装置的设计

针对目前出现的全球能源短缺危机,设计并研制了一种新型的运用海洋波浪能进行发电的振荡浮子式波浪能发电装置。简要介绍该装置的基本组成和确定转换装置的方案,完成转换装置的结构设计,并对装置的工作过程进行了说明。结合海浪理论与计算原理、海洋波浪能转换以及机械设计等知识并运用MATLAB软件编程计算装置的整机理论效率。假设装置在规则线性波浪的作用下,通过理论计算,该装置在波浪周期为5 s,波浪高度为1.5 m,浮子直径为0.2 m,长度为0.3 m的条件下,整机理论效率可达0.393。该装置具有很好的发电效率,并且装置的结构可靠性高,具有广阔的发展前景。     

Liquid hydrogen as a fuel for the future

The use of liquid hydrogen as a long-term replacement for hydrocarbon fuel for land and air transportation seems technically feasible. It is an ideal fuel from the standpoint of a completely cyclic system, serving as a "working substance" in a closed chemical and thermodynamic cycle. The energy-per-unit-weight advantage (a factor of 3) over gasoline or any other hydrocarbon fuel makes liquid hydrogen particularly advantageous for air craft and long-range land transport. As a pollution-free fuel, it must be seriously considered as the logical replacement for hydrocarbons in the 21st century.     

Global iron connections between desert dust, ocean biogeochemistry, and climate

The environmental conditions of Earth, including the climate, are determined by physical, chemical, biological, and human interactions that transform and transport materials and energy. This is the "Earth system": a highly complex entity characterized by multiple nonlinear responses and thresholds, with linkages between disparate components. One important part of this system is the iron cycle, in which iron-containing soil dust is transported from land through the atmosphere to the oceans, affecting ocean biogeochemistry and hence having feedback effects on climate and dust production. Here we review the key components of this cycle, identifying critical uncertainties and priorities for future research.     

A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides

A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.     

Energy use in rural India

An old saying has it, "slavery will persist until the loom weaves itself." All ancient civilizations, no matter how enlightened or creative, rested on slavery and on grinding human labor, because human and animal muscle power were the principal forms of energy available for mechanical work. The discovery of ways to use less expensive sources of energy than human muscles made it possible for men to be free. The men and women of rural India are tied to poverty and misery because they use too little energy and use it inefficiently, and nearly all they use is secured by their own physical efforts. A transformation of rural Indian society could be brought about by increasing the quantity and improving the technology of energy use.     

KIF1A alternately uses two loops to bind microtubules

The motor protein kinesin moves along microtubules, driven by adenosine triphosphate (ATP) hydrolysis. However, it remains unclear how kinesin converts the chemical energy into mechanical movement. We report crystal structures of monomeric kinesin KIF1A with three transition-state analogs: adenylyl imidodiphosphate (AMP-PNP), adenosine diphosphate (ADP)-vanadate, and ADP-AlFx (aluminofluoride complexes). These structures, together with known structures of the ADP-bound state and the adenylyl-(beta,gamma-methylene) diphosphate (AMP-PCP)-bound state, show that kinesin uses two microtubule-binding loops in an alternating manner to change its interaction with microtubules during the ATP hydrolysis cycle; loop L11 is extended in the AMP-PNP structure, whereas loop L12 is extended in the ADP structure. ADP-vanadate displays an intermediate structure in which a conformational change in two switch regions causes both loops to be raised from the microtubule, thus actively detaching kinesin.     

酒精提纯新工艺研究

用极性化学膜进行多级分离酒精的新工艺，所得产品纯度高，且设备简单，所需外界温度低，具有较高的社会、经济和生态效益。     

宁夏盐池四墩子草地农业生态系统辅助能的投入效率分析及评价

四墩子草地农业生态系统的土、草、畜三位一体的生产格局已形成了自给型的农业、商品型的畜牧业和保护型的林业这样一个荒漠绿洲型的草地农业生产雏形。系统内总辅助能、有机能、工业能和油料电力能的输入量分别与初级产品能的输出量呈极显著相关关系(P≤0.01);化肥能和人畜役能的输入量都与初级产品能输出量相关显著(P≤0.05)。每单位有机能和化肥能的投入,可相应获得2.41和18.59个单位的初级产品能输出。     

四川省布拖县风能资源局地调查评估

采用四川省布拖县2012年1月1日-2012年12月31日期间的A和B测风70m和10m高度实测逐时数据,通过布拖县气象站1981-2010年间的逐时风速观测数据,用长年代法进行订正和推算,对该研究区域风能资源参数进行计算.结果表明:A测风塔区域10m高度风能资源应用于并网风力发电为"好"的等级,B测风塔区域70m和10m高度分别为"好"和"很好"的等级,具有较好开发潜力,且风能和风向较为集中,有利于风机布设.测风塔地处高海拔地形较为平坦的山脊地带,临近公路,不占用耕地,气候较为温和,利于风电场修建.     

Crystal structure of the maltose transporter in a pretranslocation intermediate state

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters convert chemical energy from ATP hydrolysis to mechanical work for substrate translocation. They function by alternating between two states, exposing the substrate-binding site to either side of the membrane. A key question that remains to be addressed is how substrates initiate the transport cycle. Using x-ray crystallography, we have captured the maltose transporter in an intermediate step between the inward- and outward-facing states. We show that interactions with substrate-loaded maltose-binding protein in the periplasm induce a partial closure of the MalK dimer in the cytoplasm. ATP binding to this conformation then promotes progression to the outward-facing state. These results, interpreted in light of biochemical and functional studies, provide a structural basis to understand allosteric communication in ABC transporters.     

能源植物分类及其转化利用

能源植物及其生产是生物质能源的发展基础,也有利于减少温室气体排放、发展低碳经济。在分析总结当前国内外能源植物主要概念的基础上,利用植物系统法、光合途径、生活周期和化学成分组成及其利用等方法对能源植物进行了分类。如以化学成分组成及其利用可将能源植物分为糖料植物、淀粉植物、油料植物、含油微藻植物和木质纤维素植物5类,各类能源植物各有其主要特点。对能源作物的转化利用技术及其产品现状和前景进行系统的分析,目前由生物质转化的液体燃料主要包括乙醇、生物柴油和生物质裂解油,由生物质转化的气体燃料包括生物质燃气、沼气和氢气,生物质经压缩成型或炭化工艺可生产生物质颗粒,生物质以热电联产技术经直燃可大规模发电和供暖。     

基于“生命树”生态循环系统模型的旅游地形象策划系统研究

旅游地形象策划是对旅游地资源和旅游地市场的抽象化,是一种概念化的印象,具有独特的精神价值,并通过不同的表现手段展现给旅游者。该研究建构了一个具有生命力的形象策划系统,该系统包括理念、行为、视觉、传播,情感、意向等一系列元素,并且这些元素在系统中的能级、活跃性、生命力等多项指数各不相同,它们之间能够进行能量上的传递、信息上的反馈和生命力的扩张,以使旅游地的形象始终充满鲜活性。笔者从生态学中引入＂生态系统模型＂后,构建＂生命树＂生态循环系统模型,分别从＂系统构成＂、＂能级金字塔＂、＂循环关系＂、＂策划流程＂4个方面解析＂生命树＂生态循环系统模型,通过该模型的构建将旅游地形象策划的各环节相互衔接,形成一套标准的策划流程。     

基于模糊PID的混合储能技术在微电网中的应用

基于成本和控制效果考虑,单一的储能元件无法抑制全频段的功率波动,普通的协控制策略又无法实现实时调节参数以适应微电网随环境的变化,本文提出将基于模糊PID的混合储能的技术应用到微电网中,先从系统的构成和工作原理出发,分析混合储能技术在微电网中的应用,而后根据系统的构成和数学模型提出基于模糊PID的协调控制策略,并将此策略应用到光伏系统的仿真中,根据仿真结果的对比分析,系统的输出功率波动得到更好的抑制,储能元件有更好的运行特性,体现了该种方法的优越性。     

Unclicking the click: mechanically facilitated 1,3-dipolar cycloreversions

The specific targeting of covalent bonds in a local, anisotropic fashion using mechanical methods offers useful opportunities to direct chemical reactivity down otherwise prohibitive pathways. Here, we report that embedding the highly inert 1,2,3-triazole moiety (which is often prepared using the canonical "click" coupling of azides and alkynes) within a poly(methyl acrylate) chain renders it susceptible to ultrasound-induced cycloreversion, as confirmed by comprehensive spectroscopic and chemical analyses. Such reactivity offers the opportunity to develop triazoles as mechanically labile protecting groups or for use in readily accessible materials that respond to mechanical force.     

生物分子马达动力冲程研究

通过建立肌球蛋白工作循环的四态模型,利用化学动力学方法和生化热力学原理,计算了动力冲程的大小不仅依赖于动力冲程过程的反应平衡常数及动力冲程前态的分离速率常数,还与肌球蛋白横桥的弹性系数有关。同时,讨论了肌球蛋白横桥的弹性系数与力的关系,为试验研究提供理论依据。     

东北农户屋顶太阳能发电系统设计

为了提高太阳能发电的效率和太阳能发电系统的自动化程度,根据东北农户的特点,设计了可以自动追踪日光的太阳能发电自动控制系统。设计共分为三大部分,分别为太阳能发电系统、向光追日控制系统、自动清理系统。详细介绍了太阳能发电系统的基本组成和工作原理,给出了具体的设计方案。该系统自动化程度较高,并且满足了东北农户的能源需求,具有广泛推广的价值。     

用于就仓干燥的太阳能辅助热泵系统

针对粮食就仓干燥的特点,提出一套由太阳能辅助热泵干燥装置、通风地上笼送风系统以及粮食翻滚搅拌机械组成的就仓干燥工艺,可实现粮食就仓干燥的低能耗性、短周期性、均匀性等。以昆明地区为试验基地,设计制造了一套太阳能辅助热泵就仓干燥系统,分析了其运行性能与干燥能耗情况。给定条件下,初步研究结果表明,太阳能分数为15%,系统COPS可以达到5.19,而单位能耗除湿量可以达到3.05kg/kWh。     

基于余热回收的粮食烘干系统的设计与实现

[目的]利用收割机工作时的尾气余热及冷却水余热实时烘干粮食,避免农民收割后再次晾晒粮食的环节。[方法]设计一种基于余热回收的粮食烘干系统。该系统主要由气气换热器和水气换热器两级串联组成,利用封闭工作腔内工作介质的相变循环实现收割机的尾气和冷却水的余热回收,烘干系统的热缓苏仓以回收的热量作为热源,通过热缓苏仓降低粮食湿度,并通过冷缓苏仓冷却粮食,从而降低粮食的发芽率。[结果]该系统性能良好,可有效提高农业燃油的利用率,避免能源浪费的同时也降低了农业生产的劳动强度和劳动成本。[结论]该研究可为粮食干燥技术研究提供新思路。     

捡拾器实验台的研制(1)

本文就捡拾压捆机的主要工作部件捡拾器，能在实验室的条件下模拟它的实际运动，并能进行综合性的机械测试和物料遗漏率的测试。笔者在本文主要论述了捡拾器实验台的总体布置、原动机的选择，以及电器控制线路设计。经过试制和实际工作运行，均满足要求，可以做为教学设备和捡拾器科学研究的基本装置。