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991.
系统在SQLite嵌入式数据库基础上构造了一个s3C44B0X+uCLinux+SQLite+Boa的嵌入式家庭网关。以嵌入式微处理器S3C44B0X为中心设计硬件平台,裁减和移植uCLinux作为嵌入式操作系统,以公共网关接口(CGI)原理为基础,以SQLite为数据存储及管理后台,用软件编程的方法实现用户、嵌入式Bob服务器、网关应用程序以及信息家电之间的动态交互。  相似文献   
992.
本文主要讨论EPS电机驱动的反馈电流控制的两种方法:软件控制和硬件控制.PID控制技术成熟、鲁棒性好,在电机控制中得到了广泛的应用,在EPS软件电流控制方法中,结合EPS特点,分析PID软件控制原理和控制参数确定方法.在EPS硬件电流控制方法中,分析硬件电机电流反馈控制原理图,讨论各模块电路设计方案,通过主观评价实验得出:低速的电控单元,硬件控制电机效果较好.  相似文献   
993.
Treatment of airways disease is directed towards improving patients' health and well-being. Measurements of airways function do not reflect all the disease activity present in the airways that may affect the patient. Spirometry correlates poorly with health. Physicians appear to estimate their patients' health using criteria different from the patients themselves. Quality of life questionnaires provide a method of quantifying the effect of disease on patients' lives. They can summarize a number of aspects of the disease and provide an overall estimate of the effect of disease and benefits due to therapy. They have the potential to identify a threshold response to treatment that may be considered "worthwhile", and allow comparison between therapies with respect to the health gain that each provides.  相似文献   
994.
Tympanoplasty for sinus tympani retraction may result in delayed recurrence of the original problem. This is especially true in children with marginal eustachian tube function. Autogenous tragal cartilage, scored on one surface with perichondrium attached on the other, produces a "natural bend" in the cartilage. When placed in the middle ear, with the scored convex surface facing the promontory, retraction into the sinus tympani can be prevented. This simple, yet effective, surgical technique is outlined.  相似文献   
995.
BACKGROUND: To identify predictors of long-term outcome after balloon aortic valvuloplasty, we analyzed data on 674 adults (mean age, 78 +/- 9 years; 56% were women) undergoing this procedure at 24 clinical centers who had a mean initial increase in aortic valve area of 0.3 cm2. METHODS AND RESULTS: Baseline data included clinical, echocardiographic, and catheterization variables. Follow-up data included mortality, cause of death, rehospitalization, 6-month echocardiography, and functional status. Kaplan-Meier curves and log-rank tests were used to evaluate survival in subgroups. Multivariate Cox regression models were used to identify independent predictors of survival. Overall survival was 55% at 1 year, 35% at 2 years, and 23% at 3 years, with the majority of deaths (70%) classified as cardiac by an independent review committee. Rehospitalization was common (64%), although 61% of survivors at 2 years reported improved symptoms. Echocardiography at 6 months (n = 115) showed restenosis from the postprocedural valve area of 0.78 +/- 0.31 cm2 to 0.65 +/- 0.25 cm2 (P < .0001). With stepwise multivariate analysis, sequentially adding clinical, echocardiographic, and catheterization variables, the overall model identified independent predictors of survival as baseline functional status, baseline cardiac output, renal function, cachexia, female gender, left ventricular systolic function, and mitral regurgitation. Baseline and postprocedural variables were examined to identify which subgroup of patients has the best outcome after aortic valvuloplasty. A "lower-risk" subgroup (28% of the study population), defined by normal left ventricular systolic function and mild clinical functional limitation, had a 3-year survival of 36% compared with 17% in the remainder of the study group. CONCLUSIONS: Long-term survival after balloon aortic valvuloplasty is poor with 1- and 3-year survival rates of 55% and 23%, respectively. Although survivors report fewer symptoms, early restenosis and recurrent hospitalization are common.  相似文献   
996.
Supervisory control using variable lookahead policies   总被引:1,自引:1,他引:0  
This paper deals with the efficient on-line calculation of supervisory controls for discrete event systems (DES's) in the framework of limited lookahead control policies (or LLPs) that we introduced in previous papers. In the LLP scheme, the control action after a given trace of events has been executed is calculated on-line on the basis of anN-step ahead projection of the behavior of the DES. To compute these controls, one must calculate after the execution of each event the supremal controllable sublanguage of a finite language with respect to another finite larger language. In our previous work, we showed how the required supremal controllable sublanguage calculation can be performed by using a backward dynamic programming algorithm over the nodes of the tree representation of these two languages. In this paper, we pursue the same approach for the calculation of LLP controls, but instead we adopt a forward calculation procedure over theN-level tree of interest. This forward procedure improves upon previous work by avoiding the explicit consideration of all the nodes of theN-level tree, while still permitting tree-to-tree recursiveness as enabled events are executed by the system. The forward search ends whenever a control decision can be made unambiguously or whenever the boundary of theN-level tree is reached, whichever comes first. This motivates the name Variable Lookahead Policy (or VLP) for this implementation of the LLP supervisory control scheme. This paper presents a general VLP algorithm and studies the properties of several special cases of it. The paper also discusses the implementation of the VLP algorithms and presents computational results regarding the application of these algorithms to a time-varying DES.  相似文献   
997.
通过赤天化推行全面质量管理从而建成全国化工行业中唯一的“双满意”企业的事例,阐述了创造优质名牌产品能够促进企业兴旺的道理。  相似文献   
998.
Measurement of the local cerebral metabolic rate of glucose (LCMRGlc) and the individual rate constant parameters of the [(18 )F]2-fluoro-2-deoxy-D-glucose (FDG) model can provide a clearer understanding and insight to the physiological processes in the human brain, and a quicker and more accurate means of diagnosis in clinical applications. A systematic study using simulated and clinical tissue time activity data is presented to evaluate several existing and newly developed major algorithms used for determining LCMRGlc and the individual rate constants from positron emission tomography dynamic data. The computational and statistical properties of the autoradiographic approach, weighted and unweighted nonlinear least squares methods, Patlak graphic approach, weighted integration method, linear least squares and generalized linear least squares methods are investigated and discussed in this paper.  相似文献   
999.
The branching patterns formed as a result of crack growth in dimethacrylate resins below their glass transition temperatures looked similar to fractal trees. The skeletons of the patterns were analysed numerically for their topological and geometrical properties. The number of branches, N i , mean branch lengths, N i , and branch angles of a particular order, defined according to the Strahler and inverted Weibel schemes, followed exponential scaling behaviour: N i (R b )i and L i (R l ) i . Using the relationship for the fractal dimension D=In R B /In R L , a value of D=1.4 was obtained for the fracture pattern. Fractal behaviour was also examined by the box-counting method which indicated a power-law dependence of the mass on the box size with fractal dimension exponent D=1.4 in the case of the fracture pattern. However, the mass-shell method for both the fracture pattern and the fractal trees gave an exponential increase of mass with distance from the origin, rather than the power-law behaviour expected for fractals. This was attributed to the fact that branches of different sizes were distributed in restricted regions of space closer to the periphery, rather than uniformly over the whole pattern.  相似文献   
1000.
施怡然  卢胜  黄峰 《移动信息》2024,46(1):201-203
针对云数据中心数据获取效率低和服务器资源浪费问题,为优化云平台的数据访问和资源利用,文中提出了一种时延优化的云数据中心数据放置(LOP)方法。文中首先分析了云平台的性能,建立了云平台的资源利用和数据获取时间模型。然后基于非支配排序算法NSGA-Ⅲ实现了全局最优的数据放置策略,对数据资源进行合理部署,有效利用服务器的资源,提高了数据获取的效率。最后通过CloudSim仿真平台,对提出的数据放置方法进行了仿真和对比实验。实验结果表明,LOP方法能明显提高云服务器的资源利用率,缩短任务的数据获取时间。  相似文献   
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