计划烧除的作用与应用研究综述

计划烧除是管理森林可燃物、预防森林火灾发生的有效方法,同时也是防治病虫害、促进山林复壮更新的重要措施。文章回顾了计划烧除在国内外的发展历史,阐述了计划烧除的应用及研究,总结出实施计划烧除的主要技术及操作程序,论述了国内目前计划烧除应用研究中存在的问题及发展前景。     

塞罕坝机械林场地表可燃物类型划分与载量研究

对塞罕坝机械林场8个林分类型108个林班的地表森林可燃物组成、载量、含水率等进行了调查。结果表明落叶松成林和幼林、樟子松成林和幼林、针叶混交林、桦次生林等林分地表可燃物以枯落物为主,栎次生林和灌木林地表可燃物由枯落物与灌木组成,未成林地与草地可燃物以草本植物为主;地表可燃物载量依次为落叶松成林〉落叶松幼林〉针叶混交林〉樟子松成林〉樟子松未成林〉针阔混交林〉桦次生林〉樟子松幼林〉落叶松未成林〉灌木林〉栎次生林〉草地;草地与栎次生林的含水率最低,着火点也最低,火险危险程度最高;将现有林分按燃烧类型划分为5个类型20个亚类,全场地表可燃物总载量约为2．5×10^6t。     

高原地区沼气—柴油双燃料发动机的研究

高原地区大气稀薄,空气压力相对较低,会影响发动机的过量空气系数和充量系数,同时,沼气相对天然气可燃成分甲烷含量低,会造成发动机功率下降。针对西北高原地区的特点,文章分析了几种柴油天然气双燃料发动机改装方案,对发动机供气系统、供油系统等进行设计研究,研究了一种能适用于该地区的、成本较低的柴油沼气双燃料发动机,提出了一种氢气高压直喷系统,可提高该发动机的动力性和对各种工况的强适应性,节省开发时间,降低成本。     

国内外生物质固体燃料成型设备开发进展

总结了生物质固体燃料成型设备的国内外研究进展,并分析了我国生物质成型燃料存在的问题和今后发展方向。      

高压双电磁阀控制燃油系统控制策略研究

根据双电磁阀控制燃油系统的工作原理,讨论了可采用的溢流控制阀(SV)和针阀控制阀(NCV)控制模式;针对不同的控制模式,分析了从控制信号到燃油喷射的延时特性,揭示了动态喷嘴启喷压力(NOP)随转速的变化规律,探讨了双阀燃油系统的燃油喷射特性,并进行试验。结果表明SV相对于NCV的控制角度差值能够有效地改变NOP、NCP(喷嘴关闭压力)和MFIP(平均燃油喷射压力)的大小。着重探讨了双阀燃油系统的控制算法,阐述了NCV目标喷油持续期和目标喷油提前角的控制方法,提出了NOP控制及双阀燃油系统总体控制策略,并给出了反映NOP随转速和控制角度差值变化而变化的NOP控制MAP,为双阀燃油系统的整车应用提供了基础。     

Effects of Particle Size and Processing Variables on the Properties of an Extruded Catfish Feed

Abstract

A catfish feed was extruded to determine how particle size, moisture content and screw speed affected the pellet durability, water stability index, and buoyancy. Increasing moisture content from 250 to 300 g/kg required less die pressure, specific mechanical energy and product temperature to produce durable pellets that were stable in water. Increasing screw speed from 200 to 400 rpm also lowered die pressure, due to a lower filled length of the extruder screw channels, but increased specific mechanical energy and product temperature; the resulting pellets had a lower apparent bulk density, but a higher degree of starch gelatinization and water stability index. Reducing particle size from 1200 to 700 m decreased die pressure and apparent bulk density, but increased product temperature, degree of starch gelatinization, pellet durability index and water stability index.     

秸秆颗粒燃料密度及成粒率影响因素的研究

以玉米秸秆为原料,利用环模制粒机,进行颗粒燃料制备试验.通过单因素试验考察原料含水率、粒径和发酵时间对秸秆颗粒燃料密度和成粒率的影响;采用二次回归正交旋转组合试验,建立各因素与秸秆颗粒燃料成粒率间关系的数学模型,分析各试验因素影响成粒率的重要程度.通过优化计算,确定秸秆颗粒燃料成粒率最高时的因素优化参数为:原料含水率20％,发酵时间4h,粒径1.66mm,此时秸秆颗粒燃料成粒率为97.53％.试验验证结果表明,最优参数组合实测值与预测值相一致.     

木质纤维素为原料的燃料乙醇预处理技术研究进展

详细介绍了纤维素原料预处理方法,并对各种方法的优缺点进行了分析和讨论。     

欧洲木质颗粒燃料产业发展现状与启示

欧洲是全球木质颗粒燃料产业发达地区.文中介绍欧洲木质颗粒燃料市场总体情况、生产特征、消费特征和价格体系, 分析其为规范和引导发展木质颗粒燃料产业而在原料收集、燃料燃烧、能源服务等3个环节采取的政策措施, 从统筹环境保护与经济发展角度提出对我国发展木质颗粒燃料产业的启示.     

Sage Grouse Groceries: Forb Response to Piñon-Juniper Treatments

Juniper and piñon coniferous woodlands have increased 2- to 10-fold in nine ecoregions spanning the Intermountain Region of the western United States. Control of piñon-juniper woodlands by mechanical treatments and prescribed fire are commonly applied to recover sagebrush steppe rangelands. Recently, the Sage Grouse Initiative has made conifer removal a major part of its program to reestablish sagebrush habitat for sage grouse (Centrocercus urophasianus) and other species. We analyzed data sets from previous and ongoing studies across the Great Basin characterizing cover response of perennial and annual forbs that are consumed by sage grouse to mechanical, prescribed fire, and low-disturbance fuel reduction treatments. There were 11 sites in western juniper (Juniperus occidentalis Hook.) woodlands, 3 sites in singleleaf piñon (Pinus monophylla Torr. & Frém.) and Utah juniper (Juniperus osteosperma [Torr.] Little), 2 sites in Utah juniper, and 2 sites in Utah juniper and Colorado piñon (Pinus edulis Engelm). Western juniper sites were located in mountain big sagebrush (A. tridentata ssp. vaseyana) steppe associations, and the other woodlands were located in Wyoming big sagebrush (A. tridentata ssp. wyomingensis) associations. Site potential appears to be a major determinant for increasing perennial forbs consumed by sage grouse following conifer control. The cover response of perennial forbs, whether increasing (1.5- to 6-fold) or exhibiting no change, was similar regardless of conifer treatment. Annual forbs favored by sage grouse benefitted most from prescribed fire treatments with smaller increases following mechanical and fuel reduction treatments. Though forb abundance may not consistently be enhanced, mechanical and fuel reduction conifer treatments remain good preventative measures, especially in phase 1 and 2 woodlands, which, at minimum, maintain forbs on the landscape. In addition, these two conifer control measures, in the short term, are superior to prescribed fire for maintaining the essential habitat characteristics of sagebrush steppe for sage grouse.