Production of Levulinic Acid from Bagasse and Paddy Straw by Liquefaction in the Presence of Hydrochloride Acid     

Lifeng Yan  Naikun Yang  Hao Pang  Bing Liao 《洁净——土壤、空气、水》2008,36(2):158-163

A method of levulinic acid production from bagasse and paddy straw is presented. Biomass waste was mixed with hydrochloride acid and water, and then liquefied at about 200°C in a pressurized reactor. Both the mass of the biomass and the amount of hydrochloride acid were kept as constants, and the effects of temperature, reaction time, and acid concentration on the levulinic acid yield were studied. It was found that the yield of levulinic acid was maximum when the reaction temperature was carried out for 45 min at 220°C using 4.45% concentration of hydrochloride acid, and the maximum yields of levulinic acid were 22.8 and 23.7% for bagasse and paddy straw, respectively. The products were analyzed using NMR, HPLC, and GC/MS.  相似文献   

Simulation of near source ground motion and its characteristics     

S. Suzuki  K. Asano 《Soil Dynamics and Earthquake Engineering》2000,20(1-4)

It is fact that the severe ground motions of shear waves have a strong effect on the dynamic behavior of buildings and civil structures. We simulate near source strong motions of a pure shear wave and synthesize small motions, using the parameters based on the recorded accelerograms at the site that is regarded as a base rock in the Osaka basin, Japan. By making use of a stochastic technique, we can easily introduce higher frequency contents in the motions and apply the technique to the synthesis of small waves regarding as a green function. We also introduce to the analysis the useful relationships among the time duration T_d, the seismic moment M₀, the corner frequency f_c and the high cutoff frequency f_max which were regressed by a simple representation scheme. Considering two active faults that may affect severe damage on buildings and civil structures, we try to predict strong ground motions in Osaka basin and show the characteristics of them.  相似文献   

全球变化的集成研究   总被引：19，自引：4，他引：19  

葛全胜  陈泮勤  张雪芹 《地球科学进展》2000,15(4):461-466

在论述全球变化集成研究的理论基础——复杂性科学的基础上,概述了国际全球变化集成研究的含义、现状与方向,讨论了中国全球变化集成研究的现状,并展望了中国全球变化集成研究的切入研究命题。  相似文献   

气候变化科学的最新认知   总被引：239，自引：22，他引：217  

秦大河  陈振林  罗勇  丁一汇  戴晓苏  任贾文  翟盘茂  张小曳  赵宗慈  张德二  高学杰  沈永平 《气候变化研究进展》2007,3(2):63-073

 政府间气候变化专门委员会（IPCC）第一工作组于2007年2月2日发布的第四次评估报告明确指出,近100 a（1906-2005年）地球表面平均温度上升了0.74℃,近50 a的线性增温速率为0.13℃/10 a,1850年以来最暖的12个年份中有11个出现在近期的1995-2006年。全球变暖已经是不争的科学事实,报告认为人类活动是近50 a全球气候系统变暖的主要原因。 IPCC评估报告是国际科学界对气候变化问题最权威、最全面的认识,代表了目前全球气候变化研究的科学认识水平,是国际上制定相关政策的重要依据。  相似文献   

一种新的预报晴空湍流综合算法   总被引：2，自引：0，他引：2  

沈强  沈文武 《气象与减灾研究》2009,32(2):44-49

介绍了晴空湍流及其相关的湍流指数,以及通过对9个指数进行加权综合得到的一个综合预报算法。利用T213模式资料,计算了9个湍流指数,并分别用12个北京地区的飞机颠簸个例进行验证,得到各湍流指数的预报结果;在此基础上,应用新的综合算法,得到一个综合预报结果。计算结果表明,虽然理查孙数和风相关指数、MOSCAT概率预报因子指数的预报效果相对较好,但是这三个指数的预报范围和强度均偏大,容易出现空报;综合算法则较好地综合各个指数,预报区域相对集中,预报强度也较符合实际情况,空报的情况也得到了相应的改善,总体预报效果较好  相似文献   

SQIP方法在华北地区地震中、短期预测中的应用研究          下载免费PDF全文

周翠英  王红卫  张继红  李红  许萍 《地震工程学报》2006,28(2):167-171

对SQIP地震学中期预测方法在华北地区的中期预测效果进行了重新评价,回溯性全时空扫描检验报准率R值约为0.67~0.68。做了方法中短期和短期预测指标的提取尝试。结果表明综合参量P值异常区由最大出现收缩后,平均约7个月左右发生未来主震,其中6个月内的震例约占有“收缩”震例的53%~54%,在3个月内的约占33%~35%;部分震例发生在异常区消失后7~8个月内。表明P值异常区“收缩”(或消失)一定程度上可以作为中、强地震的中短期预测标志。  相似文献   

谈谈“地震速报评比软件”及其研制     

李华  周峰嵘  郑黎辉  孙则兴 《福建地震》1998,(2)

本文介绍了“地震速报评比”的重要性及“地震速报评比”软件的研制及使用效果。认为用该软件进行速报评比可使评比结果更公正、准确,评比工作效率也可以大大提高。  相似文献   

Response to Thrift's “The future of geography”     

B. L. Turner II 《Geoforum》2002,33(4):427-429

Reviews and observations about the status of the discipline of geography, no matter how positive, invariably raise programmatic concerns. These concerns have a long history that arise from geography's struggles to find an identity that embraces its many parts and yet are consistent with the logic by which the academy partitions knowledge. Pedagogy and research historically claimed by geography is currently being reinvented and relabeled under such headings as “integrated environmental science” and “spatial science”, and these developments have the potential to change the breadth of the “geographic imagination”. Several observations about dominant explanatory perspectives and substantive domains of geographic enquiry are also provided.  相似文献   

美国长期生态学研究网络的战略规划——走向综合科学的未来   总被引：2，自引：0，他引：2  

于秀波  付超 《地球科学进展》2007,22(10):1087-1093

从2004年11月起至今,美国长期生态学研究网络在美国国家科学基金会的资助下,为未来(几)十年的综合和网络层面研究进行了战略规划.规划的最终目标是形成一个新的长期生态学研究(LTER)网络层面科学计划,并通过1个科学课题组、7个网络科学工作组和一系列研讨会来进行.在制定和完善科学计划的过程中,规划行动获得了LTER网络层面科学的跨学科问题、概念框架、基本科学问题、社会与环境综合科学动议、网络计算机基础设施的战略规划、教育与宣传战略规划等重大科学产出.规划的意义在于它告诉了怎样走向LTER的未来--网络层面综合科学,因而有利于LTER及长期生态研究的发展,并可为CERN等其他长期生态学研究网络的规划与发展提供启示.  相似文献   

Textural properties vs. CEC and EGME retention of Na–X zeolite prepared from fly ash at room temperature     

Arkadiusz Derkowski  Wojciech Franus  Halina Waniak-Nowicka  Adriana Czímerová 《International Journal of Mineral Processing》2007

Zeolite Na–X (FAU type) was synthesized from F-class fly ash in simple and economical way. Several months of storage of fly ash in NaOH solution, at room temperature, without any prior treatment, results in the production of material with ca. 50% content of Na–X zeolite. The most efficient reaction takes place at (OH)⁻ activity of 0.1–0.15 mol (OH)⁻/g of ash and at S/L ratio of 33 to 67 g/dm³. Higher S/L value causes an accelerating dissolution–crystallization equilibrium attainment. Cl⁻ ion acts as the inhibitor of this reaction.  相似文献