3种水草腐解对水质的影响

为了探究河蟹生态养殖池塘常见的3种水草腐解对水质的影响,进行了为期60 d的室内桶装模拟试验,监测水草质量损失率和桶内水体水质指标的变化。结果表明:3种水草的腐解速率有相同的特点,即前期较快,中、后期较慢,同时也存在差异性,轮叶黑藻和伊乐藻的腐解速率相近且较快,金鱼藻最慢;试验结束时,轮叶黑藻、伊乐藻和金鱼藻的质量损失率分别达到72.3%±2.1%、71.7%±1.5%和58.3%±0.6%。腐解前期水质因子的变化较大,水体由中性变为酸性;3种水草水体化学需氧量较试验初期升高约4.5倍,水体发黄、发臭;溶解氧被极大地消耗,水体处于缺氧或厌氧环境,促进了反硝化的进行,硝氮迅速降低,而亚硝氮和氨氮迅速升高,其中氨氮约是初始含量的6倍;总氮、总磷升高明显,其中总磷在所有水质因子中变化幅度最大,第3天,轮叶黑藻、伊乐藻和金鱼藻处理组水体总磷分别增加约123、124和66倍。随着腐解的进行,水体的部分氮、磷沉积进入底泥。总而言之,较多的水草残留在池塘中,会引起水体缺氧,加剧植物残体的腐解,导致水质恶化,因此需要适时地通过人工打捞来控制水草残体的生物量。     

Ultralow friction of carbonate faults caused by thermal decomposition

High-velocity weakening of faults may drive fault motion during large earthquakes. Experiments on simulated faults in Carrara marble at slip rates up to 1.3 meters per second demonstrate that thermal decomposition of calcite due to frictional heating induces pronounced fault weakening with steady-state friction coefficients as low as 0.06. Decomposition produces particles of tens of nanometers in size, and the ultralow friction appears to be associated with the flash heating on an ultrafine decomposition product. Thus, thermal decomposition may be an important process for the dynamic weakening of faults.     

森林凋落物及其分解过程的研究进展

森林凋落物是林地有机质的主要来源,其凋落量及分解过程对森林生态系统物质循环和能量流动影响极大。文章综述了森林凋落物的概念、组成及控制凋落量的主要因素;指出凋落物自身特性尤其是化学特性以及土壤生物、气候、土壤理化性质、人类活动等外部环境条件是影响凋落物分解的主要因子;分析了现阶段反映凋落物分解状况的分解率概算模型、时间衰退模型和影响因子关系模型;提出在全球环境变化背景下,森林凋落物各组分之间交互效应对其分解过程的影响,将是今后研究的热点。     

喹诺酮类(吡哌酸、诺氟沙星)药物的热分解特性研究

分别采用差示扫描量热法(DSC)、热重法(TG)和微分热重法(DTG),研究了喹诺酮类(吡哌酸、诺氟沙星)抗菌药的热分解动力学过程,计算了其热分解动力学参数——活化能(E),分析了其热分解机理,并剖析了喹诺酮类药物有机结构上的差异。     

低温送风空调的送风设计与研究

对一空调工程进行了常规送风与低温送风气流组织设计比较，对末端不加诱导器或混合箱，直接用普通定风量散流器送风的低温送风空调的气流组织形式进行了可行性分析研究，比较分析了散流器结构类型、尺寸、特性参数，送风速度、送风温度，风口布置间距等因素对低温送风气流组织的影响．认为直接用普通径向贴附散流器可以满足低温送风气流组织要求，并为设计提供了参数选择指导．     

煤矿瓦斯水合分解过程热量传递机理研究进展

我国瓦斯资源丰富,传统工业技术不能对瓦斯进行有效利用,已成为煤层气工业发展的瓶颈.应用水合物技术对瓦斯进行处理与储运,为煤层气工业的发展注入新的生机.综述了非瓦斯类气体水合物形成和分解过程热量传递控制机理的研究进展,分析了深入开展煤矿瓦斯水合分离过程水合物分解传热机理研究的必要性,指出基于三维温度场试验测试设备,系统研究煤矿瓦斯组分、促进剂等影响条件下水合分解过程的温度场分布,探寻热量传递与瓦斯水合分解反应之间的耦合作用关系,是亟待解决的关键科学问题.     

Foliage temperature extraction from thermal imagery for crop water stress determination

Crop water stress determination methods from canopy temperatures, derived from the surface energy balance equations, treat the canopy temperature under the assumption that the canopy behaves as a virtual “big-leaf”, covering the ground surface. Introduction of very high-resolution thermal imagery, 0.01–0.3-m pixel size, acquired from low altitude platforms, enabled finely detailed observation of the whole canopy, raising the question how to select the relevant canopy temperatures. One approach is to select the sunlit leaves confirming to the “big leaf” energy balance paradigm. However, thermal imagery alone is incomplete and needs additional marking or synchronized visible imagery for interpretation, which makes the process complicated and expensive. The other approach, used in reference surface based water stress evaluation, is to use full frame pixel statistics without pattern recognition by selecting the mean temperature of the cold fraction from the pixel histogram. That greatly simplifies processing for large-scale aerial thermography. Here are presented the results of experiments conducted in cotton and vine grapes, where both approaches were evaluated simultaneously. Ground referenced thermal and visible images were overlapped, and sunlit, shaded and whole canopy leaves were selected for crop temperature evaluation. The pixel histograms of the same images were analyzed in a two-step method, after discarding soil pixels where their temperature was 7 °C higher than air temperature at step one, and calculation of the mean temperatures of the lowest 33 and 100 % of the remaining pixels for step two. Several crop water stress indices were compared with leaf and stem water potentials and stomatal conductance. Good agreement was found between both image segmentation and histogram analysis methods, demonstrating the suitability of both methods in canopy temperature evaluation for crop water stress evaluation.     

The thermal stability of water ice at the poles of mercury

Recent radar observations of Mercury have revealed the presence of anomalous radar reflectivity and polarization features near its north and south poles. Thermal model calculations show that, despite Mercury's proximity to the sun, the temperatures of flat, low-reflectivity surfaces at Mercury's poles are not expected to exceed 167 kelvin. The locations of the anomalous polar radar features appear to be correlated with the locations of large, high-latitude impact craters. Maximum surface temperatures in the permanently shadowed regions of these craters are expected to be significantly colder, as low as 60 kelvin in the largest craters. These results are consistent with the presence of water ice, because at temperatures lower than 112 kelvin, water ice should be stable to evaporation over time scales of billions of years.     

梯度热水处理减轻低温贮后的黄瓜果实冷害

为探讨梯度热水处理对贮后黄瓜品质的影响及冷害减轻机理,以4℃贮藏4d后不做热处理的黄瓜为 对照(CK),研究了梯度热水处理TG,10(Temperature gradient 10)(黄瓜依次在14、24、34和44℃分别浸泡4 min;),TG,20(黄瓜依次在24和44℃分别浸泡8 min)和TG,40(黄瓜在44℃下浸泡16 min)后对贮后黄瓜(4℃±0.5℃、湿度85％±5％)失重率、冷害指数(Chilling injury,CI)、质构特性、电解质外渗率(Electrolyte leakage,EL)和丙二醛(Malondialdehyde,MDA)含量等指标的影响.结果表明:TG,10和TG,20处理组黄瓜相比于CK,果实硬度、可溶性固形物和可溶性蛋白含量显著提高,冷害指数、失重率、电解质外渗率和丙二醛含量显著下降;而TG,40处理黄瓜相比于CK品质更差.说明适当梯度的热水处理可能使低温贮后黄瓜冷害发生一定程度的减轻,从而延缓了果实可见性冷害的发生,有利于维持果实品质,提高果实的商品价值.研究可为梯度热水处理在贮后果蔬保鲜中的应用提供理论参考.     

水、氮耦合对阔叶红松林叶凋落物分解的影响

以长白山阔叶红松林优势树种红松、蒙古栎、色木槭、水曲柳、紫椴的叶凋落物为研究对象,定量模拟加水、加氮、凋落物量对凋落物分解和土壤碳氮过程的影响。结果表明:加氮处理对凋落物分解没有显著影响, 凋落物量增多使分解率下降, 加水处理显著促进水曲柳凋落物的分解。培养结束后,凋落物的氮质量分数增加、碳质量分数和C/N降低,凋落物残体的δN值因凋落物种类、水氮处理的不同而不同,δC值下降, 土壤的碳、氮质量分数增加,δN值无显著变化,δC值和C/N下降。      

高浊度黄河水作为管道试压用水的处理工艺

针对西气东输二线东段13B标段水资源匮乏的现状,探讨了利用灌溉区内高浊度黄河水作为水源的可行性工艺.高浊度黄河水处理试验采用聚氯化铝混凝沉淀强化工艺,对比分析了加入自然沉淀型聚氯化铝前后,不同沉淀时间的水质情况及沉淀水质的成分.结果表明:只有加入自然沉淀型聚氯化铝沉淀2h后的水质能够满足西气东输二线的试压用水要求;不加入任何沉淀药剂,仅依靠自然沉降3h,无法满足要求.依据试验结果,制定了利用高浊度黄河水作为试压用水的工艺流程,解决了水资源匮乏地区试压用水的施工难题.     

芦笋混浊汁的生产工艺研究

本试验比较了两种加工工艺对芦笋混浊汁风味的影响，探讨了影响芦笋混浊汁贮存稳定性的因素。结果表明：同采用传统阿氏杀菌的芦笋混浊汁相比，应用巴氏瞬时杀菌的芦笋混浊汁具有浓郁的芦笋风味，无异味；均质或添加耐酸羧甲基纤维素钠(CMC－Na)、海藻酸丙二醇酯(PGA)、黄原胶等稳定剂能明显提高芦笋混浊汁贮存的稳定性。     

Thermochemical decomposition of water based on reactions of chromium and barium compounds

A potentially useful thermochemical cycle developed for the production of hydrogen and oxygen from water consists of three chemical reactions that take place in the temperature range from 400 degrees to 1200 degrees K. The oxidation and reduction of chromium compounds by barium hydroxide and the hydrolytic disproportionation of barium chromate(IV) and barium chromate(V), the reactions which constitute the proposed cycle, have been demonstrated.     

水资源开发中水环境保护措施研究

水资源是地球上人类离不开的重要资源,保护水资源是人类共同的责任。人类在开发利用水资源的同时,不能忽视由此而引发的水环境问题。从国内外主要河流因不合理开发而产生的环境问题出发,阐述了在进行水利工程建设、开发利用水资源的同时,应注重水环境和生态系统的保护,并根据我国的实际情况,提出水环境保护的内容和3点具体措施。     

海湾扇贝多糖水提工艺研究

利用正交试验法对海湾扇贝多糖水提工艺进行优化,以多糖提取率为指标,研究了温度、料液比、时间对提取效果的影响。结果表明:最佳水提工艺为:提取时间为6 h,温度为90℃,料液比为1∶40,多糖提取率为5.419%,为海湾扇贝产品开发提供依据。     

微波辅助水抽提葛根有效成分工艺的优化

经正交试验,得出以水为溶剂微波辅助提取葛根有效成分的最佳试验条件为微波功率510 W,微波处理时间15 min,重复处理2次.与有机溶剂95%乙醇溶剂相比,提取率相差不大.     

凝视热成像系统仿真软件

现代高科技的发展离不开系统的理论指导及计算机模拟。通过研究热成像系统原理，用VC 语言编制了一个热成像系统仿真软件包。该软件包除了可以计算热成像系统包括MRTD，MTF，NETD，MDTD，视距等的静态性能参数外，还有一个非常创新的特点：它允许用户输入原始图像，在选定的热成像系统的作用下，用户可以得到被所选定的热成像系统任何模块（如大气、光学系统，探测器、电子学等）处理过的图像，真实直观地观察各个模块对图像的影响，这对热成像系统设计指导和分析有关更深的指导意义。     

凝视热成像系统仿真软件

现代高科技的发展离不开系统的理论指导及计算机模拟。通过研究热成像系统原理，用VC 语言编制了一个热成像系统仿真软件包。该软件包除了可以计算热成像系统包括MRTD，MTF，NETD，MDTD，视距等的静态性能参数外，还有一个非常创新的特点：它允许用户输入原始图像，在选定的热成像系统的作用下，用户可以得到被所选定的热成像系统任何模块（如大气、光学系统，探测器、电子学等）处理过的图像，真实直观地观察各个模块对图像的影响，这对热成像系统设计指导和分析有关更深的指导意义。