Real time servo control of the holographic data storage system with an additional servo beam

Holographic data storage is a next generation data storage device, which has high storage density, high data transfer rate and short access time. The device is very sensitive to disturbances due to its enormous storage density. In the disk type holographic data storage device deviation occurs successionally on the position of the data as the disk rotates. Therefore the spot where the probe beam is illuminated should directly be corrected in order to exactly retrieve the desired data. In this paper we suggest a method using an additional beam containing a servo pattern in order to detect the deviation of the media. We also propose a real time servo control method to compensate the affect of the unpredicted disturbance.     

New multiplexing method of holographic data storage system

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time. Today any data storage system cannot satisfy all of these conditions, however holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanically actuating part therefore fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this research, to record and retrieve binary data by a new hologram multiplexing in our holographic data storage system, we propose a new multiplexing method that is cyclone multiplexing method. Also, three algorithms were integrated in our holographic data storage system.     

An intelligent distortion-detection algorithm for restoring data in a holographic data storage system

In a holographic data storage system (HDSS), misalignment of the optical components causes data distortion, including barrel, pincushion, and rotation distortion. Because holographic data storage systems are very sensitive, misalignment inevitably results in data distortion. It is important to acquire accurate distortion-free data from a HDSS system. This paper proposes an intelligent distortion-detection algorithm for restoring data in HDSSs. We used a fuzzy system and subtractive clustering algorithm to generate fuzzy rules for the detection algorithm. The proposed algorithm determines a value indicating how distorted the data image is. Using this algorithm, it is possible to compensate for data distortion. A simulation performed well using barrel, pincushion and rotation images.     

Design of tracking servo control system for holographic data storage

Holographic data storage is a strong candidate for the next generation archive storage device. However, disturbances such as external shock, vibration, flutter and eccentricity of the disk affects the holographic data storage device. Thus, tracking servo control is necessary in order to enhance the signal noise ratio and reduce the bit error rate and retrieve the data accurately. It is also inevitable to face track overlapping problem if there is no datum to apply servo control during the recording process. In this research, we suggest a method forming a holographic servo track to detect the tracking error signal continuously without using any additional laser diode or pre-format layer. The tracking servo controller is designed to improve the track following performance, and the validity of the proposed method is confirmed through experiments on our holographic data storage system.     

Suggest a format for intelligence control and structure of holographic data storage system

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time. Today any data storage system cannot satisfy all of these conditions, however holographic data storage system (HDSS) can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanically actuating part therefore fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this research, to reduce errors of binary data stored in HDSS, a new method for bit error reduction is suggested. Firstly, find fuzzy rule using test bed system for Element of Holographic Digital Data System and make fuzzy rule table using subtractive clustering algorithm and genetic algorithm and Reduce prior error element and recording digital data. Secondly, Reduce prior error element and recording digital data using the particle filter method. Finally, Recording ratio and reconstruction ratio show good performance and we suggest intelligence control method and filter method. Our format table include intelligence control algorithm and filter method.     

Tilt detection and servo control method for the holographic data storage system

Recently photopolymer with disk type substrate is selected as a media of the holographic data storage system. Because shape of the media is a disk, a disk tilt must be occur when the media rotates. When disk tilt occurs the angle between the reference beam and the media is changed by the tilt, thus the data can not be recorded with a right angle or another data page is retrieved. The holographic data storage system is very weak to the tilt disturbance by the Bragg effect, therefore it is necessary to detect the disk tilt angle and compensate it. In this study, we measure the amount of the tilt error using external photo detector and compensate it by rotating the angle of galvano mirror with our own algorithm.     

Tracking servo method using reflective optical filter for holographic data storage system

Holographic data storage system is one of the next-generation data storage systems and is characterized by its high storage density and fast data transfer rate. However, holographic data storage systems are very sensitive to disturbances that affect the position of the media. Therefore, tracking servo control is needed to ensure a good performance of the system even if disturbances occur, such as eccentricity of the disk and external shock. In our previous researches on tracking servo methods, we used additional beams or recorded servo track images with data pages to record additional gratings with data pages. Therefore, the recording density may be reduced and the system may be complicated. In addition, the performance of the system may be compromised by cross-talk noise caused between the reference beams and additional beams. In this paper, we propose a tracking servo method using the residual beam, which is reflected by the reflective optical filter. This method does not require recording supplementary gratings or use additional beams, and only needs to record data pages. The residual beam is retrieved with desired retrieved beam by the reference beam and wasted during the retrieving process. We first constructed a holographic data storage system and designed a reflective optical filter to detect tracking error signals. After detecting the tracking error signals, a tracking servo controller using a lead-lag compensator was incorporated to reduce the tracking error signals. The performance of the designed controller was verified by simulated and experimental results. Finally, the performance of the tracking servo method was investigated by comparing the retrieved data images.     

Generation of fuzzy rules and learning algorithm for servo control in holographic data storage system

Today many media of information storage device are formed as disks. Hence, next generation removable data storage media are shaped as disk types too. The holographic data storage system also uses a disk type photopolymer media. And then, holographic data storage system is most advanced optical memory system. Tracking servo and tilt servo control are very important research in holographic data storage system. In this paper, we propose intelligent servo control by fuzzy rules in holographic data storage system. Hence, we have found pattern of tilt servo control in holographic data storage system through fuzzy system and genetic algorithm. Fuzzy rules were generated by genetic algorithm for controlling tilt servo. Therefore, we control tilt servo using fuzzy rules in holographic data storage system. Consequently, Image input–output patterns of tilt servo control was found by intelligence algorithm in holographic data storage system.     

Specificities of data page representation in projection type optical holographic memory system

The matter of the present article covers the results obtained during the development of holographic memory record system based on projection of computer-generated amplitude Fourier holograms. The basic issue is the investigation of representation specificities of binary data pages, which were choose to be encoded on computer-generated amplitude Fourier hologram and then recorded on photosensitive medium as microhologram using simple projection optics and spatial light modulator. Limitations of data page resolution caused by limited resolution of SLM that is used to display the digitally synthesized holograms are discussed. Also the results of random phase coding of data page during the holograms synthesis research are presented.     

电能表系统数据存储的研究

为了解决电能表系统数据现场升级程序容易出现数据混乱的问题,分析了目前电能表系统数据存储的方式,针对目前电能表系统数据存储的问题提出了改善方案。通过数据链表创造出一个可以自由伸缩的数据存储系统,形成了以数据块为存储单元的存储模式,解决了电能表系统中新增加数据会导致现有数据地址改变的问题。文章先从目前电能表系统数据存储的问题说起,随后提出了新的数据存储模型,并一一介绍了新数据存储模型的创建、读取、写入及删除等操作,并在电能表上成功实现了新数据存储模型。     

实时控制系统中数据的实时分片存储

为了在不影响实时控制系统响应时间的前提下实时地保存数据,提出了一种基于分片的数据实时存储方式.通过在实时控制系统中添加存储节点,在实时控制的过程中,实时节点将数据按时间分片,传给存储节点,存储节点采用分片存储的方式保存到存储系统中.这种方式只需要占用实时控制节点很少的控制周期时间,结合新增的存储节点完成对实时数据的存储,能在控制过程中实时读取分析数据.该方式应用于东方超环(EAST)等离子体控制系统上,能够较好的实现对长脉冲放电和未来的稳态放电实验数据进行实时的存储和读取分析,也能为其他实时控制系统的数据的实时存储提供借鉴.     

Iterative design method for an image filter to improve the bit error rate in holographic data storage systems

An image filter design method is proposed to improve the bit error rate (BER) in holographic data storage (HDS). In previous image restoration methods for HDS, a highly precise point spread function (PSF) was used as the deconvolution filter, so performance was strongly dependent on the accuracy of the PSF. In the proposed method, in contrast, the image filter is designed without using PSF information, due to the similar spatial frequency distributions of HDS data pages. A simple iteration algorithm was developed to obtain an optimized image-filter shape, and the performance of the designed image filter was verified by both simulation and experimentation. The experimental results demonstrated that the BER improved sixfold and greater than tenfold for a Nyquist factor of 1.1 and 1.2, respectively. Additionally, an improvement of >30 % in storage density was projected using the proposed filter, compared with conventional HDS systems.     

集群存储系统数据安全研究

借鉴P2P的思想实现了一个基于集群的安全存储系统,并介绍了构建在该存储体系结构之上的一种数据安全存取方案.引入基于共享鉴别密钥的鉴别机制,以确保用户数据的授权访问,防止未授权用户的阅读和修改.系统采用广泛用于加/解密技术中的SHA-1算法作为密码校验函数,与采用数字签名鉴别机制相比,该算法具有较高的性能.初步分析和实验表明,该系统在现实条件下,在消耗较低的维护带宽的同时维持了较高的可靠性,并提供了较好的读写性能.     

基于曲率补偿的电流基准源的设计

提出了一种利用分支电流的正负温度系数进行温度补偿的新型设计方法。在传统的电流温度补偿的基础上,通过增加一条分支电流对温度特性进行曲率补偿(二阶温度补偿),并且详细地分析了补偿原理。使用XFAB公司的0.6μm CMOS工艺模型进行仿真模拟,得到了较好的仿真结果:在-40℃～135℃温度范围内,其温度系数达到39.8ppm/℃。     

卷取机PDA数据采集系统的开发

针对由高精度传动控制、位置控制、压力控制以及快速连锁控制等组成的卷取控制系统，介绍了开发PDA数据采集系统的组态、网络集成和软件配置等，以及分析系统的组态和分析方法的应用。该项目解决了过程数据的高速采集、存贮和分析技术等难题，为分析设备和工艺控制状况，提供了技术平台和分析手段，解决了生产过程数据的录入难题，具有推广应用价值。     

Minimax control of a process in a linear uncertain-stochastic system with incomplete data

Consideration is given to the control problem in a linear stochastic differential system where constant noise intensities in equations of state and observation are prescribed only accurate within the membership of some known sets. For control optimization, an integral root-mean-square performance criterion is used. The problem is solved by the transition to a dual one, which makes it possible to prove the existence of a saddle point of the criterion and obtain an explicit expression for the minimax control operator as functions of the solution to the dual problem. To solve the latter, an iteration algorithm is proposed; the convergence of the algorithm is proved and investigated by a model example.     

视频数据的存储调度优化策略

文章论述了采用多个代理服务器的视频点播系统中负载平衡的基本原理,指出了现有动态均衡解决方案存在的问题,各节点机的负载评价问题和任务迁移的抖动问题,进一步分析了负载接入量和接入许可问题,以及文件存储的静态调整技术.同时提出了以节目点播概率为参数,周期性调整系统中的节目文件存储,以便使用户的点播请求合理分配到各视频服务器,从而实现整个系统的负载均衡的基于点播率的存储动态调整算法.     

化工过程数据处理系统的开发

介绍了运用FORTRAN和C Builder语言开发的化工过程数据处理系统。分别描述了该系统中4个功能模块的结构及其可实现的计算功能,然后提出了模块链接设计思想并开发出窗体界面,最后通过计算实例说明了该系统在化工数据处理中的应用,计算结果表明该系统能够满足化工数据处理的要求。