水-水热泵系统全年性能优化的研究

在热泵系统仿真模型的基础上,结合典型建筑物的全年负荷预测,提出了热泵系统全年季节性能优化的理念,定义了热泵全年性能系数APF,并以此为优化目标函数,换热器面积比为优化变量,研究在压缩机开停控制方式下系统的优化匹配,并与以HSPF、SEER和EER为优化目标的优化计算进行对比,结果表明,采用APF作为优化目标具有更加真实客观的节能效果。     

全厚度缝合复合材料泡沫芯夹层结构力学性能研究与损伤容限评定

探索了全厚度缝合复合材料闭孔泡沫芯夹层结构低成本制造的工艺可行性及其潜在的结构效益。选用3 种夹层结构形式, 即相同材料和工艺制造的未缝合泡沫芯夹层和缝合泡沫芯夹层结构及密度相近的Nomex 蜂窝夹层结构, 完成了密度测定、三点弯曲、平面拉伸和压缩、夹层剪切、结构侧压和损伤阻抗/ 损伤容限等7 项实验研究。结果表明, 泡沫芯夹层结构缝合后, 显著提高了弯曲强度/ 质量比、弯曲刚度/ 质量比、面外拉伸和压缩强度、剪切强度和模量、侧压强度和模量、冲击后压缩(CAI) 强度和破坏应变。这种新型结构形式承载能力强、结构效率高、制造维护成本低, 可以在飞机轻质机体结构设计中采用。      

断裂输导体系输导天然气效率评价方法及其应用

为了研究断裂输导体系垂向输导天然气的效率,在分析断裂输导能力影响因素的基础上,提出了断裂输导体系输导系数的概念。根据天然气成藏过程的有效性,建立了断裂输导体系输导效率评价标准,并将其应用于库车坳陷北带断裂输导体系输导效率评价中,结果显示该坳陷北带天然气的分布与断裂输导体系输导系数分布具有较好的相关性,表明该评价方法用于评价断裂输导体系的输导效率是可行的。     

模糊综合评判方法判断低效循环井层

疏松砂岩油藏注水开发后期,在油水井之问形成了储层大孔道,导致注入水沿大孔道做低效循环,油井产量下降。为改善注水效果达到控水稳油目的,必须采取低效循环井层调剖、封堵等措施,而有效识别低效循环井层是问题的关键。通过分析大孔道形成的影响因素以及在开发中表现出的特征,确定出低效循环油水井判定指标,利用模糊综合评判方法初步选定低效循环油水井。然后通过小层静态数据与沉积微相对比,以及油水井的相 关性对比,最终确定出低效循环井层。基于此方法编制成软件,对大庆油田北三东东块低效循环井层进行了判断,与人工选择结果对比符合率为81．7％。该方法切实可行,并且大大提高了工作效率和客观、准确性。
     

FCC装置三旋效率低的原因及对策

针对中国石油抚顺石化分公司石油二厂催化裂化装置再生器第三级旋风分离器(三旋)效率低的问题,对三旋的运行状况进行了分析和核算,找出了原因,认为主要问题是烟气中催化剂细粉较多、粒度大,以及三旋单管烟气线速较低和单管排尘锥体处粉尘返混严重.采取堵管和排尘锥体开孔的措施后,实际运行结果证明,三旋效率提高了,三旋出口烟气中催化剂浓度、粒度达到标准,保证了烟气轮机的安全平稳运行.     

油水分离旋流器流场和分离性能的数值模拟

深入研究了液-液水力旋流器的流动机理,并采用LRR应力模型对油水分离旋流器的油水两相流场进行了数值模拟。通过数值计算得到了水力旋流器内流体流动的流线图、等压线以及速度矢量图,并且研究了不同参数(分流比、进口压力以及溢流管直径)对分离效率的影响。计算结果与理论分析一致,证明了模型和算法的正确性。研究成果为前人试验和理论总结提供了有力的理论支持,同时为进一步研究水力旋流器的分离机理、流场特性以及结构优化设计提供了一条有效的途径。     

波动方程数值模拟的隐式差分法

在有限差分波动方程数值模拟中,通常采用高阶差分方法来提高空间导数的数值逼近精度,以实现降低数值频散,提高数值模拟精度的目的。首先对差分频散进行了理论分析;然后讨论了估计一阶空间导数的隐式差分格式,并与通常采用的高阶精度显式差分格式进行了对比分析,结果表明,隐式差分格式能够在更宽的波数范围使差分频散控制在可接受的水平,如8阶精度的显式差分格式所适应的波数带宽约为O．55kmax,而隐式差分格式所适应的波数带宽约为0．7kmax;最后通过模型试算,对隐式差分格式的有效性进行了验证。模拟结果表明,用隐式差分格式在一定程度上降低了差分频散,提高了模拟精度。     

Energy efficient distributed steganography for secure communication in wireless multimedia sensor networks

A secure communication mechanism is necessary in the applications of Wireless Multimedia Sensor Networks (WMSNs), which is more vulnerable to security attacks due to the presence of multimedia data. Additionally, given the limited technological resources (in term of energy, computation, bandwidth, and storage) of sensor nodes, security and privacy policies have to be combined with energy-aware algorithms and distributed processing of multimedia contents in WMSNs. To solve these problems in this paper, an energy efficient distributed steganography scheme, which combines steganography technique with the concept of distributed computing, is proposed for secure communication in WMSNs. The simulation results show that the proposed method can achieve considerable energy efficiency while assuring the communication security simultaneously.     

Design of high efficiency dual-mode buck DC-DC converter

A buck DC-DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current,and it can operate with an input range of 4.5 to 30 V.At light load current,the converter operates in skip mode.The converter enters PWM mode operation with increasing load current.It reduces the switching loss at light load and standby state,which results in prolonging battery lifetime and stand-by time.Meanwhile, externally adjustable soft-start minimizes the inru...     

EACLE : Energy-Aware Clustering Scheme with Transmission Power Control for Sensor Networks

In this paper, we propose a new energy efficient clustering scheme with transmission power control named “EACLE” (Energy-Aware CLustering scheme with transmission power control for sEnsor networks) for wireless sensor networks, which are composed of the following three components; “EACLE clustering” is a distributed clustering method by means of transmission power control, “EACLE routing” builds a tree rooted at a sink node and sets the paths from sensor nodes taking energy saving into consideration, and “EACLE transmission timing control” changes the transmission timing with different levels of transmission power to avoid packet collisions and facilitates packet binding. With an indoor wireless channel model which we obtained from channel measurement campaigns in rooms and corridors and an energy consumption model which we obtained from a measurement of a chipset, we performed computer simulations to investigate the performance of EACLE in a realistic environment. Our simulation results indicate that EACLE outperforms a conventional scheme such as EAD (Energy-Aware Data-centric routing) in terms of communication success rate and energy consumption. Furthermore, we fully discuss the impact of transmission power and timing control on the performance of EACLE.