大动态PCM/FM遥测信号的非相干解调

针对大动态低码率PCM/FM遥测信号的可靠接收问题展开研究,给出了一种基于连续相位调制（CPM）信号原理的载波频偏矫正及差分序列检测的非相干接收方案。针对限幅鉴频、多符号检测及差分序列检测等3种非相干解调算法,介绍了各自应用于PCM/FM信号的算法原理,并比较了3种算法的解调性能及对大动态环境的适应能力。计算机仿真表明,在无残留频偏情况下,2符号相位差分序列检测性能最好;但在0.05倍码速率的残留频偏下,1符号相位差分序列检测的性能更好,优于2符号相位差分序列检测、限幅鉴频检测和多符号非相干检测。对PCM/FM信号的讨论包含了几种典型的非相干解调,对大动态环境下的PCM/FM接收有重要的参考价值。     

一种多功能井下信号转换适配器的设计与应用

为实现不同生产厂家仪器的组合测井,经常需要设计各种不同的信号格式转换器.提出并实现了一种小体积、低功耗、多功能的信号适配器,实现PCM/DTB、PCM/CAN、DTB/CAN信号之间的转换.系统采用FPGA作为DTB总线的时序控制,集成CAN协议控制器的单片机C8051F060作为CAN总线驱动和PCM信号的软编解码.通过俄罗斯感应测井仪与中国石油集团测井有限公司研制的EILog快速与成像测井系统的挂接试验验证了系统设计的可靠性与优越性.     

Investigation of tactile comfort properties of the fabrics treated with microcapsules containing phase change materials (PCMs microcapsules)

In this study, it was focused on the investigation of comfort-related properties of the fabrics treated with microcapsules containing phase change materials (PCMs microcapsules). There are limited findings about the effect of prepared PCM microcapsules on fabric properties related with the tactile comfort. In this work, we applied our produced microcapsules to the cotton fabrics and researched these fabrics’ tactile comfort-related properties such as bending rigidity, drape, fabric–fabric friction, and tenacity. One of the outstanding properties of our microcapsules is reactive carboxylic acid groups on their wall. They have the ability to bind to the fabrics in terms of their reactive chemical groups. Microcapsules on the fabrics can be durable to the effects of the rubbing and repeated washings. The fabric test results indicated that air permeability, bending rigidity, tensile strength decrease with the microcapsule treatment, whereas the fabric drape and coefficient of friction of the fabrics increase depending on the amount of microcapsules added on the fabric.     

用于相变存储器的超低输出纹波2X/1.5X电荷泵

本文针对相变存储器编程驱动电路,提出了一种超低输出电压纹波的开关电容型电荷泵。该电荷泵可根据输入电压的不同,自适应工作在2X/1.5X升压模式之间,以获得更高的电源转换效率。相比于传统开关电容型电荷泵,在充电阶段泵电容被充电至预先设定的电压值Vo-VDD(Vo为预期的输出电压);放电阶段,泵电容串联在输入电压VDD与输出端,通过此方法将电荷泵输出端电压稳定在Vo,并有效的降低了由于电荷分享所造成的输出纹波。在中芯国际40nm标准CMOS工艺模型下,对电路进行了仿真验证,结果表明在输入电压为1.6-2.1V,输出2.5V电压,最大负载电流为10mA,输出电压纹波低于4mV,电源效率最高可达91%。     

Fatty acid/poly(methyl methacrylate) (PMMA) blends as form-stable phase change materials for latent heat thermal energy storage

Fatty acids such as stearic acid (SA), palmitic acid (PA), myristic acid (MA), and lauric acid (LA) are promising phase change materials (PCMs) for latent heat thermal energy storage (LHTES) applications, but high cost is the most drawback which limits the utility area of them in thermal energy storage. The use of fatty acids as form-stable PCM will increase their feasibilities in practical LHTES applications due to reduced cost of the energy storage system. In this regard, a series of fatty acid/poly(methyl methacrylate) (PMMA) blends, SA/PMMA, PA/PMMA, MA/PMMA, and LA/PMMA were prepared as new kinds of form-stable PCMs by encapsulation of fatty acids into PMMA which acts as supporting material. The blends were prepared at different mass fractions of fatty acids (50, 60, 70, 80, and 90% w/w) to reach maximum encapsulation ratio. All blends were subjected to leakage test by heating the blends over the melting temperature of the PCM. The blends that do not allow leakage of melted PCM were identified as form-stable PCMs. The form-stable fatty acid/PMMA (80/20 wt.%) blends were characterized using optic microscopy (OM), viscosimetry, and Fourier transform infrared (FT-IR) spectroscopy methods, and the results showed that the PMMA was compatible with the fatty acids. In addition, thermal characteristics such as melting and freezing temperatures and latent heats of the form-stable PCMs were measured by using differential scanning calorimetry (DSC) technique and indicated that they had good thermal properties. On the basis of all results, it was concluded that form-stable fatty acid/PMMA blends had important potential for some practical LHTES applications such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard or floor impregnated with a form-stable PCM due to their satisfying thermal properties, easily preparing in desired dimensions, direct usability without needing an add encapsulation and eliminating the thermal resistance caused by shell and thus reducing cost of LHTES system.     

带有USB接口的16位立体声数模转换器PCM2702

PCM2702是Burr-Brown公司新近推出的一种带有USB接口的16们立体声数模转换器芯片。文中简要分析了该芯片的性能特点和工作原理,最后给出了PCM2702的典型应用电路。     

化学法和共混法制备的PEG/CDA相变材料的性能比较——微相结构与储热性能的关系

分别采用化学键联和物理共混的改性方法制备了两种相变材料 ,并用偏光显微镜和透射电镜分别对它们进行观察 ,讨论两者的微相结构差异和结构随温度的变化 ,同时研究了微相结构与储热性能的关系。结果表明 :采用化学键联法制得的相变材料具有更小、更稳定的微相区 ,并且是通过固—固相变来储能和释能的 ;而采用物理共混法制得的相变材料 ,仅仅是两种原料聚乙二醇和二醋酸纤维素的简单混合 ,实际上发生的仍为固—液相变     

电信特种业务处理系统的电话数字信息处理

以“285支票电话挂失查询系统”为例,介绍了在电信特种业务处理系统中,前端工作站对于从电话上输入的数字信息的处理。     

纳米铝粉/石蜡复合相变储能材料的性能研究

针对石蜡作为固-液相变储能材料存在导热系数小、传热性能差的缺点,采用两步法制备了分散性较好的纳米铝粉/石蜡复合相变材料,并对其热物性能进行了实验研究.研究表明,纳米铝粉的加入有效地提高了石蜡相变储能材料的导热系数,而对相变潜热和相变温度影响不大.     

Thermal performance of packed bed thermal energy storage units using multiple granular phase change composites

The present article reports on the utilization of multiple granular phase change composites (GPCC) with different ranges of phase change temperatures in a packed bed thermal energy storage system. Small particle diameter of GPCC allows simple mixing of two or three ranges of GPCCs in a packed bed for enhancement of storage unit performance. Experiments have been carried out to characterize the phase changing characteristics of two GPCCs chosen for this purpose. Packed bed column experiments have been carried out to provide basic understanding of the heat transfer process in the composite bed consisting of a mixture of GPCCs at different values of mixing ratio. A mathematical model has been developed for the analysis of charging and discharging process dynamics. Once validated, the model has been used to perform a parametric study to investigate the overall bed performance at different values of mixing ratio and Reynolds number. An optimization of the value of mixing ratio has been obtained based on the overall charging and discharging times as well as the exergy efficiency. It has been demonstrated that, as compared to the use of single GPCC, careful choice of the mixing ratio of GPCCs in a composite bed can result in a significant enhancement of the overall storage unit performance. As compared to the use of multiple sequential layers of GPCCs, using units composed of a mixture of GPCCs with an optimized mixing ratio results in a remarkable improvement of the unit performance without limitations on the charging and discharging directions during practical applications.