大水深测量校正方法研究与应用

水库水深测量精度直接关系到水库的防洪安全与蓄水兴利。现有回声测深仪无法应对大水深施测的情况，且测量受到水库水温分层影响。利用回声测深仪配合校正标进行大水深测量的校正方法，能够精确检测到回声测深仪水深测量的误差及差值、系统延时问题等，通过与各级校正标的真值比较、修正，能使测值近似真值,且使误差控制在容许范围内。介绍了水深校正标基本原理、操作方法和步骤以及在水库测深中的应用。     

水蓄冷运行控制分析

随着空调蓄冷技术的不断发展,它已逐渐在节能效果、经济效益和社会效益等方面展现出强大的生命力和广阔的市场。主要探讨了自然分层蓄冷形式,该方式利用温度和密度不同的原理,通过斜温层分隔高、低温水。必须严格进行水蓄冷系统的运行控制,否则极易打破其自然分层的规律。     

基于堆积床相变蓄热的模型验证及堆积优化

针对堆积床相变蓄热罐,建立二维非稳态连续固相模型,对其蓄热特性进行数值研究。通过模拟结果揭示了蓄热过程中斜温层的变化情况以及换热温差的分布状态。探究了初始温度、传热流体进口温度、相变胶囊直径对蓄热性能的影响,并将所得结果与已有文献进行对比验证。为进一步提高堆积率,结合颗粒堆积理论,提出颗粒直径服从Alfred分布的堆积优化方案。模拟结果显示,该优化方式在蓄热时间少量增加的情况下能显著提高蓄热量,具有很好的优化效果。     

负跃层条件下浅海海底单参数反演技术

海底参数反演是获取海底声学特性一种经济高效的办法。近年来,课题组提出用小掠射角下海底反射损失随掠射角的变化率F_dB（dB·rad^-1）作为描述海底的单参数,建立了浅海均匀水层和负跃层水文条件下的海底单参数模型。负跃层单参数模型的建立,为海底单参数反演提供了新的设计思路。文章基于浅海负跃层海底单参数模型,设计海底单参数地声反演方法。首先对负跃层水文条件下浅海海底单参数模型进行简单的描述和介绍;然后在浅海负跃层单参数模型基础上,利用声传播损失对海底单参数进行反演;最后利用实验数据对反演方法的有效性进行了验证。     

Simulations on simultaneous charging/discharging process of oil sand packed bed thermocline storage tank

A physical mathematical model of oil sand packed bed thermal energy storage (TES) which can be applied in high temperature TES system is established. The charge/discharge outlet temperature and thermocline thickness are investigated when charge and discharge process are operated simultaneously. The results indicate that the small charging power and lower increasing rate of charge outlet temperature are obtained in the end of simultaneous charge and discharge. The smaller the net TES flow rate, the longer it takes to reach a stable charge outlet temperature under the condition of the same TES medium in the TES tank. The conventional TES tank thermocline thickness is thinner than oil sand packed bed when operated at the same net charge flow rate. The stable/unstable simultaneous charge and discharge are investigated based on cycle process of square wave thermal source. The discharge outlet temperature and the thermocline thickness gradually increase after the end of each cycle due to the effect of the superposition of the cycle process. The discharge outlet temperature fluctuates periodically.     

Thermodynamic Analysis of Packed Bed Thermal Energy Storage System

A packed-bed thermal energy storage(PBTES) device, which is simultaneously restricted by thermal storage capacity and outlet temperatures of both cold and hot heat transfer fluids, is characterized by an unstable operation condition, and its calculation is complicated. To solve this problem, a steady thermodynamics model of PBTES with fixed temperatures on both ends was built. By using this model, the exergy destruction, thermocline thickness, thermal storage capacity, thermal storage time, and other key parameters can be calculated in a simple way. In addition, the model explained the internal reason for the change of thermocline thickness during thermal storage and release processes. Furthermore, the stable operation of the PBTES device was analyzed, and it was found that higher inlet temperature of hot air, and lower temperature difference between cold and hot air can produce less exergy destruction and achieve a larger cycle number of stable operation. The work can be employed as the basis of the design and engineering application of PBTES.     

高温熔融盐斜温层单罐蓄热的热过程特性

以斜温层蓄热单罐设计理念为基础,采用硝酸熔融盐作为传热蓄热介质,锆质蓄热球与泡沫碳化硅陶瓷2种代表性的多孔介质填料作为固体蓄热体,构建了多尺度结构斜温层混合蓄热方法及系统,实验研究了多尺度结构中熔融盐的流动与蓄热特性。研究结果表明,由于斜温层的存在,系统理论蓄热效率小于80%;相对于熔融盐单相流体蓄热,采用锆质蓄热球与泡沫碳化硅的斜温层混合蓄热方式会导致系统的有效蓄热容量有所降低,但多孔介质填料的加入有利于保持熔融盐流体为理想的重力流或活塞流,并部分替代价格较高的熔融盐,需要结合蓄热容量以及经济性进行最优化设计。     

Rat behavioral thermoregulation integrates with nonshivering thermogenesis during postnatal development.

Rat pups are capable of behavioral thermoregulation, both in the nest and on a thermocline, as early as the 1st week of postnatal life, and these pups can also produce heat metabolically without shivering. The rat pup's primary source of nonshivering thermogenesis is the sympathetically mediated metabolism of brown adipose tissue (BAT). BAT is well formed in newborns and functions shortly after birth. While infant behavioral thermoregulation and BAT thermogenesis have been extensively studied, little is known about the extent to which thermoregulatory behavior can be influenced by BAT thermogenesis. In the present study, 2-, 7-, and 14-day-old pups were observed on a thermal gradient following pharmacological stimulation or inhibition of BAT thermogenesis, and their thermal preferences were quantified. The authors found that 7- and 14-day-old pups treated with norepinephrine (NE), which increases BAT thermogenesis, preferred cooler portions of the gradient than saline-treated controls, whereas 2-day-olds failed to show a similar NE-induced behavioral adjustment. These findings indicate that the ability to adjust thermoregulatory behavior to compensate for enhanced metabolic thermogenesis develops during the 1st week of postnatal life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

松涛水库水温数值模拟研究

为研究热带地区湖泊型水库水温分布规律,以海南省松涛水库为研究对象,采用垂向一维水温模型——DYRESM模拟水温分布,探究该水库水温结构及垂向水温年内演变规律。经分析可知:松涛水库水温呈显著的稳定分层结构,水温垂向分布具有明显的季节性;6、7月平均水温最高,2月最低,水深40 m处至库底水体水温不随时间改变,常年保持在19℃左右;全年内,水库表层水温均高于入流水温和当地气温;入库流量猛增时会导致水库水温出现双温跃层结构。     

Climate change does not explain historical changes in the pelagic ecosystem of Lake Kariba (Zambia–Zimbabwe)

Recent studies on the pelagic ecosystem of Lake Kariba identified a number of changes in its thermal regime, planktonic communities and fishery production, concluding they were the result of climate change, particularly warming. This study re‐examines these conclusions and suggests alternative explanations for these changes. Historical data suggest there was no warming of the lake until at least the 1990s. Furthermore, lack of recent data makes it difficult to conclude that the lake’s temperature has increased by 2 °C. It is also not clear that the pattern of thermal stratification has changed, or that the thermocline has risen and become more stable. Although one of the suggested effects of climate change was a decreased number of larger zooplankton, this change occurred in the 1970s, when there had been no change in the lake temperature. Rather, there is strong evidence that the zooplankton composition changed as a result of selective predation by the introduced clupeid, Limnothrissa miodon. Furthermore, the loss of large grazing zooplankton species could have affected the composition of the phytoplankton, although this phenomenon also has been attributed to climate change. Although the phytoplankton communities in the lake are not as well documented as the zooplankton communities, it is clear that many changes in the lake actually began in the 1970s. Finally, the decline in the pelagic fishery for Limnothrissa was also linked to temperature changes. However, because the fisheries on the Zambian and Zimbabwean sides exhibited very different behaviours, there is little evidence to support this conclusion. It is concluded that the impacts of climate change on Lake Kariba are likely to be complex and that possible over‐simplification in identifying these impacts will not facilitate our understanding of these complexities.