狭缝调相式气动分置式斯特林制冷机的调相器理论

给出的狭缝调相式气动分置式斯特林制冷机,具有阻尼调节方便、造价低、制作与装配简单等优点。该机使用调节件与气动腔体之间的缝隙替代气动杆上的干摩擦来调节排出器的运动阻尼,进而调节排出器与活塞之间的运动相位差。主要给出了狭缝调相器的理论模型,并针对不同间隙进行了性能模拟与试验验证。试验结果与性能模拟结果符合很好,证明了所建立理论模型的可行性。     

狭缝调相式分置斯特林制冷机理论模型与模拟

自从分置式斯特林制冷机出现以来,工程设计对可靠的整机理论模型有着迫切需求。给出狭缝调相式气动分置式斯特林制冷机热动力学模型及控制方程,直线压缩机采用了绝热模型,压缩活塞的运动规律采用了试验修正,模型中考虑了活塞驱动电机运动特征和回热不完全、轴向导热、穿梭运动、气体泵热、辐射等主要冷损,排出器运动采用单自由度强迫运动模型,并运用数值计算方法模拟整机性能。该模型可用来对整机性能进行预测并帮助设计者深入理解整机物理过程。     

大冷量分置式斯特林制冷机

多元器件和焦平面阵列技术的蓬勃发展,要求制冷机提供较大的制冷量来满足系统的需要。本文充分介绍了国内外大冷量斯特林制冷机的研制情况,并在继承已有成熟技术的前提下,提出了研制大冷量分置式斯特林制冷机所需解决的关键技术,最后概述了国内外在斯特林制冷机方面的理论研究情况和发展趋势。     

小型分置式斯特林制冷机的研究概述

自逆向斯特林循环被用做制冷获得成功以来,斯特林制冷机已经历了近半个世纪的发展。目前,斯特林制冷机已成为小型低温制冷机中被研究得最深入、应用最广泛、发展最成熟的制冷机。本文从分析小型分置式斯特林制冷机的原理出发,介绍了国外研究情况,阐述了小型分置式斯特林制冷机研究的关键技术和当前的一些相关研究。     

分置式斯特林制冷机耦合间隙对探测器性能的影响

分置式斯特林制冷机作为红外探测器组件的重要组成部分,在实际应用中对红外探测器组件的性能影响较大。其中,分置式斯特林制冷机与杜瓦耦合时的耦合间隙是对红外探测器组件的性能影响最大的因素之一。因此针对二者的耦合间隙对探测器性能的影响进行了实验研究。当芯片温度为75 K且制冷机的冷头温度为70 K时,模拟仿真冷指与杜瓦的变形量,耦合间隙变形为0.0096 mm。低温环境对制冷机冷指与杜瓦变形的影响较小,可以忽略冷指与杜瓦变形对耦合间隙的影响。实验结果表明,红外探测器组件的降温时间随耦合间隙的增大而逐渐增大。随着时间的逐渐增大,不同耦合间隙对应的直流电流也各不相同。同一时刻下,耦合间隙越小,直流电流就越小。二极管电压随时间的增加呈现出逐渐增大并逐渐平稳的状态。在达到控温状态前,同一时刻下,耦合间隙越小,二极管电压越大。     

机载红外探测装置中的长分置管斯特林制冷机

为设计出满足应用要求的长分置管斯特林制冷机,开展了制冷机的应用背景、设计要求、结构特点、关键技术的研究,并对影响制冷机应用的各类因素进行了分析.目前该型号制冷机已应用于机载红外探测装置中,经多次试验证明,该系统重复性好,运行稳定、可靠.     

分置式斯特林制冷机气动膨胀机阶梯轴振子运动特性研究

对气动分置式膨胀机振子进行运动分析和实验验证,说明随气动杆面积增加,振子相角减小、振幅增加;将直连结构与气动杆结构制冷机性能进行对比,介绍了阶梯轴面积比会影响制冷机的压缩机和膨胀机匹配,实际研发中应结合压比、相角、振幅几方面确定阶梯轴面积;分析了阶梯轴结构膨胀机的宽频工作特性。     

焦平面探测器用集成式斯特林制冷机数值模拟计算

对焦平面探测器用集成式斯特林制冷机进行了数值模拟计算,在计算模型中加入了流动阻力,同时对如此小尺寸的制冷机进行了测试.数学模型的建立完全按照真实的斯特林制冷机结构.整个制冷机分为13个控制容积,每个控制容积都建立了质量、动量和能量守恒方程.计算程序用Visual C++和MATLAB编写,这些基本方程通过反复迭代求解.通过本计算模型与其它经典计算模型的比较,本模型更接近真实的斯特林制冷机工作情况,数值模拟计算的压力、和制冷功率等工作性能参数,与制冷机的实验测试的数据进行了对比.计算程序已用于新型号集成整体式制冷机的设计计算.     

动磁式线性斯特林制冷机仿真分析

动磁式线性斯特林制冷机是目前国际上比较流行的战术用长寿命微型斯特林制冷机.以昆明物理研究所的SCI15H动磁式线性斯特林制冷机为研究对象,对制冷机的板弹簧、磁路和热力学循环进行了仿真分析.分析方法采用了FEM(有限元法)和CFD(计算流体力学)分析方法.热力学分析'模拟了制冷机的内部流动情况和制冷量,磁路分析计算了线圈的磁感应强度和磁力线分布,板弹簧分析给出了弹簧应力分布和弹簧刚度.     

斯特林制冷机驱动器元器件的散热优化设计及试验研究

驱动器元器件的散热问题一直是斯特林制冷机在高温环境下稳定运行的主要限制因素。以某款斯特林制冷机为研究对象,通过具体的驱动器元器件的散热结构设计来优化其散热特性。通过试验验证了优化后散热结构的可靠性及散热提升效果。在热真空环境温度60℃条件下,应用这种散热优化结构的斯特林制冷机的驱动器元器件的平均温降约为7.18%。通过试验发现,在热真空环境温度60℃条件下,用紫铜作为背板材料的元器件的平均温度比用铝作为背板材料时约低9.05%;制冷机反向放置时元器件的平均温度比正向放置时约低19.25%。本文设计的散热优化结构、试验过程及结果,对具体的工程实践具有一定的指导意义。     

红外制冷机驱动系统的电磁干扰滤波器设计与仿真

完成了红外制冷机驱动系统滤波器的设计与仿真。针对系统关键器件的特性,采用合理算法建立精确的联合仿真模型。并借助联合仿真模型提取分析了系统的干扰机理。基于阻抗失配理论分析了不同滤波器拓扑的插入损耗与源和负载阻抗间的关系。最终提出了一套基于干扰机理的传导干扰滤波器设计及优化方法,该方法有效地优化了滤波器的性能,并降低了设计冗余。通过实验验证了该方法的准确性与可行性。     

Provable data possession scheme based on public verification and private verification

More and more users choose to transfer their applications and data into the cloud.Data security is a key issue for cloud storage systems.To ensure the integrity and validity of the data stored in the cloud,provable data possession (PDP) scheme is particularly important.In order to verify whether the cloud storage service provider had stored the data of the user completely,a scheme on the basis of NRPDP (non-repudiable PDP) was improved and extended,and a data retention scheme based on public authentication and private authentication was proposed.The scheme can verify the trustworthiness of the service provider and the user in the cloud storage at the same time,which satisfies the non-repudiation of the verification.The theory proves the non-repudiation of the proposed scheme.The experiment proves that the efficiency of each stage is better than that of the existing single public verification method or private authentication method.     

空间红外探测用30 K单级脉管制冷机高能效研究

建立了阻抗匹配模型,同时从冷指及压缩机两方面对制冷机性能进行优化.基于热声理论,构建了30 K温区脉管冷指的一维Delta EC理论模型,优化了惯性管型单级脉管制冷机冷指和压缩机耦合的工作参数.从机理上分析了回热器填料、双段惯性管长度及气库体积对冷指声学阻抗及压缩机声功转化效率的耦合关系.搭建实验测试平台,测试结果表明此单级脉管制冷机可以获得24.24 K的最低温度,输入功227 W时可以在30 K获得1 W冷量,可较好的满足空间红外探测器应用.     

航空电子产品焊接工艺验证方法研究

针对航空电子产品,阐述了一种相对完善的工艺验证方法,为航空电子产品制造商进行焊接工艺验证提供了指导。电子产品的类型多种多样,文章主要针对航空电子产品的特点,对其焊接工艺的验证方法进行探索和研究。     

基于VMM统一验证平台的Serdes芯片验证

本文基于VMM验证平台,介绍了高速串行收发器芯片的验证方法。文章首先简要介绍了Serdes芯片和VMM验证方法,然后搭建了Serdes芯片的VMM统一验证平台,并从测试激励产生、寄存器读写控制、覆盖率自动统计、断言验证及覆盖率收敛等几个方面详细阐述了Serdes芯片的验证过程。最后给出了验证结果和测试报告。     

Public integrity verification for data sharing in cloud with asynchronous revocation

Cloud data sharing service, which allows a group of people to access and modify the shared data, is one of the most popular and efficient working styles in enterprises. Recently, there is an uprising trend that enterprises tend to move their IT service from local to cloud to ease the management and reduce the cost. Under the new cloud environment, the cloud users require the data integrity verification to inspect the data service at the cloud side. Several recent studies have focused on this application scenario. In these studies, each user within a group is required to sign a data block created or modified by him. While a user is revoked, all the data previously signed by him should be resigned. In the existing research, the resigning process is dependent on the revoked user. However, cloud users are autonomous. They may exit the system at any time without notifying the system admin and even are revoked due to misbehaviors. As the developers in the cloud-based software development platform, they are voluntary and not strictly controlled by the system. Due to this feature, cloud users may not always follow the cloud service protocol. They may not participate in generating the resigning key and may even expose their secret keys after being revoked. If the signature is not resigned in time, the subsequent verification will be affected. And if the secret key is exposed, the shared data will be maliciously modified by the attacker who grasps the key. Therefore, forcing a revoked user to participate in the revocation process will lead to efficiency and security problems. As a result, designing a practical and efficient integrity verification scheme that supports this scenario is highly desirable. In this paper, we identify this challenging problem as the asynchronous revocation, in which the revocation operations (i.e., re-signing key generation and resigning process) and the user's revocation are asynchronous. All the revocation operations must be able to be performed without the participation of the revoked user. Even more ambitiously, the revocation process should not rely on any special entity, such as the data owner or a trusted agency. To address this problem, we propose a novel public data integrity verification mechanism in which the data blocks signed by the revoked user will be resigned by another valid user. From the perspectives of security and practicality, the revoked user does not participate in the resigning process and the re-signing key generation. Our scheme allows anyone in the cloud computing system to act as the verifier to publicly and efficiently verify the integrity of the shared data using Homomorphic Verifiable Tags (HVTs). Moreover, the proposed scheme resists the collusion attack between the cloud server and the malicious revoked users. The numerical analysis and experimental results further validate the high efficiency and scalability of the proposed scheme. The experimental results manifest that re-signing 10,000 data blocks only takes 3.815 ?s and a user can finish the verification in 300 ?ms with a 99% error detection probability.     

一种可多人验证的量子多重代理盲签名方案

多数情况下签名者只有一个人。当原始签名人无法亲自签名时,为了保证文件的有效性、防止权利过于集中,他可以委托多个人对文件进行签名和验证。方案采用量子密钥分发协议保证安全性,并利用幺正变换进行签名和验证,对签名和验证的顺序没有要求,并且签名和验证人数可以不同,提高了工作效率。正确性和安全性分析表明该方案技术实现简单,能够抵御主动和被动攻击,是一种安全的可实现量子多重代理盲签名方案。     

Formal verification of analog and mixed signal designs: A survey

Analog and mixed signal (AMS) designs are an important part of embedded systems that link digital designs to the analog world. Due to challenges associated with its verification process, AMS designs require a considerable portion of the total design cycle time. In contrast to digital designs, the verification of AMS systems is a challenging task that requires lots of expertise and deep understanding of their behavior. Researchers started lately studying the applicability of formal methods for the verification of AMS systems as a way to tackle the limitations of conventional verification methods like simulation. This paper surveys research activities in the formal verification of AMS designs as well as compares the different proposed approaches.