氟化镨钕制备方法研究比较

文章用氢氟酸法、氟化氢铵法、氟化氢气体法三种方法制备氟化镨钕工艺进行了研究对比,分别对氟化镨钕在生产中的使用效果、成本、质量、环保等方面进行了讨论,给生产和使用厂家提供参考建议。     

Decision Support System to Evaluate and Compare Concession Options

With the increased popularity of concession projects over the last three decades, there is a need for a decision support system (DSS) capable of evaluating and comparing several concession project investment (CPI) options in an effective and efficient manner. Hence, a novel DSS has been developed that takes into consideration both financial and nonfinancial aspects of the investment option, as well as the uncertainties commonly encountered during the feasibility stage of a project. The DSS is fully implemented as a standalone computer software package, ECCO (evaluate and compare concession options), in order to be of practical use. This paper outlines and validates ECCO’s design and structure through the demonstration of its capabilities in the evaluation and comparison of three real-life CPI case studies.     

Stereoacuity and colour contrast

We have measured the contrast dependence of stereoacuity using both horizontally and vertically oriented, isoluminant (red-green) and isochromatic (yellow-black), 0.5 c/deg Gabor patches. For comparison, contrasts were computed in multiples of detection threshold, where detection threshold was defined as the contrast required for the stimulus to be simultaneously detectable in each eye. Disparity thresholds (1/stereoacuity) for vertical chromatic Gabors were higher than those for vertical luminance Gabors by a factor of between 4 and 9 depending on contrast, and declined less steeply with contrast. Disparity thresholds for horizontal chromatic Gabors were very high (130-210 min arc) compared with horizontal luminance Gabors (by a factor of between 9 and 17) and were only measurable at contrasts above 10 times simultaneous monocular detection threshold. These results support the view that chromatic stereoscopic processing is less precise than luminance stereoscopic processing, and that there is a special deficit in the processing of disparity with horizontally oriented chromatic stimuli. The implications of these results for the role of colour vision in stereopsis are discussed.     

混匀料场堆位配置方案的比较

对钢铁厂混匀料场设计中不同料堆堆位配置方案进行了比较和分析,提出了满足生产工艺要求、且经济合理的混匀堆位配置建议.     

换向与不换向蓄热式燃烧技术的优劣比较

叙述了蓄热式燃烧技术的工作原理,并对燃料换向蓄热式燃烧技术和燃料不换向蓄热式燃烧技术进行了比较,发现换向蓄热式燃烧技术熔化速度快,造价高,适用于10t以上的熔铝炉;不换向蓄热式燃烧技术熔化速度慢,故障率低,适用于10t以下,特别是燃重油的小型熔铝炉。     

Stimulus orientation and contrast constancy

The human visual system requires less contrast to detect patterns oriented vertically or horizontally than those oriented obliquely. We investigated whether this orientational anisotropy persists at suprathreshold contrasts. Using a contrast-matching technique, we found that it disappears at contrasts just above threshold, given the stimulus conditions employed. These results suggest that a neural mechanism, at suprathreshold, adjusts the gain of orientational subsystems to compensate for the lower sensitivity of the visual system to oblique patterns. A similar suprathreshold effect, referred to as contrast constancy, has been observed in studies employing grating patterns varying in spatial and temporal frequency. We argue, based on previous electrophysiological findings, that this neural compensation results from antagonism between excitatory and inhibitory processes in the visual cortex.     

CO2动力学模型的比较

实验研究了850～1100℃下,稻草600℃焦、木屑500 ℃焦、宝雁煤、兖州煤和石油焦与CO2的气化反应,并分别采用了收缩未反应芯模型、混合模型和随机孔模型进行了反应速率实验数据的拟合.从数据拟合的吻合程度来看,随机孔模型与混合模型比收缩未反应芯模型拟合效果好,与其他两种模型相比,随机孔模型能够表达某些煤焦气化反应过程中出现最大反应速率的现象,这是由于随机孔模型考虑了气固相反应界面在反应过程中的变化,描述了煤焦在气化反应时微孔的发展与坍塌,比其他两种模型更准确、灵活.     

FINEX流程的特点以及与高炉流程的比较

本文介绍了FINEX流程的一些显著特点,并将FINEX流程与高炉流程从节能、环保、产品、建厂投资等方面进行了对比分析,使大家充分了解了FINEX流程的优越性以及对其进行研究开发的重要意义.     

Myocardial contrast echocardiography

MCE has evolved from a laboratory tool to a clinical procedure. It would be wrong to consider it merely another tool for imaging of myocardial perfusion. As discussed, it allows physicians to bring physiology and pathophysiology to the bedside, providing a better understanding of the underlying mechanisms of abnormal findings in individual patients. MCE can provide quantitative measurements that can be repeated as often as necessary in a patient. Because of its complexity, large clinical studies are necessary to define the role of MCE in the general clinical milieu. Advances in MCE continue at a very rapid pace, and its potential for the study of endothelial function, site-specific targeting, and local delivery of drugs appears promising. Its role will continue to evolve into the early part of the next century. What we learn of the myocardium can be easily applied to other organ systems accessible to ultrasound. The future of MCE appears very exciting.     

Behavioral contrast and behavioral momentum.

In Exp 1, 5 pigeons were trained to peck a key on multiple schedules of food reinforcement. The reinforcer rate was constant in 1 component and varied between conditions in the alternated component. In the constant component, steady-state response rate and its resistance to both prefeeding and extinction were inversely related to the reinforcer rate in the alternated component. Thus, resistance to both prefeeding and to extinction, like response rate, exhibits behavioral contrast. In Exp 2, a time-out period between schedule components eliminated contrast effects on steady-state response rate but not on resistance to extinction. The resistance-to-change results contradict expectations derived from current quantitative accounts of steady-state operant behavior and suggest instead that resistance to change depends on the contingency between component stimuli and reinforcers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

见习大学生培训效果比对分析

通过对新入职见习大学生专业知识考试成绩运用统计方法作比对分析,提出了改善培训效果应对措施,可以作为大学生见习设计的参考。     

GPS高程拟合中多面函数及二次曲面函数的比较与分析

结合某区域的GPS和水准测量数据,用多面函数法、二次曲面函数法分别进行高程拟合,结果表明,在高程异常变化较大的区域用多面函数拟合GPS高程异常时,精度较高。     

Positive behavioral contrast, negative simultaneous contrast and their relation to frustration in pigeons.

Reports results of 3 experiments with a total of 78 male Auto-Sexed King pigeons and 18 male Silver King pigeons. In Exp I positive behavioral contrast and the aversiveness of the negative stimulus varied directly with the magnitude of reinforcement. In Exp II negative simultaneous contrast was obtained in an operant analog of the discrete trials paradigm. In Exp III a reduction in the magnitude of reinforcement produced positive behavioral contrast and, concurrently, negative simultaneous contrast. The relation of behavioral and simultaneous contrast and their dependence on frustration are discussed, as well as the problem of the proper control procedures for studying behavioral contrast. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

中澳单种煤性质比较研究

介绍了国内部分地区10种炼焦煤及6种澳洲煤的特性,通过对镜质组平均最大反射率、岩相组成、硫含量、磷含量、灰成分催化系数、流动度、奥亚膨胀度等单种煤性质的测定及单种煤炼焦试验,对比澳洲煤与国内煤差异,通过比较发现,对焦炭质量有积极贡献的指标澳洲煤大多优于国内煤。     

圆管拉拔配模两种计算方法的比较和分析

本文通过理论推导证明了在一定条件下等比递减计算法实质上就是等差递减计算法，两者具有内在联系。实例计算也证明了这一点。本文还对这两种计算法进行了分析比较，认为等差法（KD-KS计算法）优于等比法（如ZBL法），前者可为优化圆管拉拔配模规程创造有利条件。     

测定钢铁及合金中酸溶铝方法的比较

对光度法,滴定法,ICP—AES,ICP—MS这几种常用测定钢铁及合金中酸溶铝方法的优缺点,方法要点和干扰情况以及消除干扰的办法进行了比较和研究。着重研究了ICP—AES法的干扰情况以及消除干扰的办法。     

Sensitivity of enhanced MR in multiple sclerosis: effects of contrast dose and magnetization transfer contrast

BACKGROUND AND PURPOSES: New strategies have been developed to improve the sensitivity of contrast-enhanced MR imaging in quantifying disease activity in patients with multiple sclerosis (MS). The goal of the present study was to evaluate the sensitivity of T1-weighted images after injection of a triple dose of contrast material and application of a magnetization transfer (MT) pulse in the detection of enhancing lesions as compared with the conventional approach. METHODS: Monthly MR images were obtained in 13 patients with relapsing-remitting MS for a period of 3 months. The MR studies were performed on two separate occasions with single- and triple-dose contrast material. In each session, T1- and T2-weighted spin-echo images with and without the MT pulse were obtained before and after contrast administration. All images were evaluated in a blinded fashion and scored in random order and consensually by two readers. The number of total and new enhancing lesions and active images was counted. RESULTS: Eighty-six percent more enhancing lesions and 54% more new enhancing lesions were detected with triple-dose as compared with single-dose non-MT sequences, whereas single-dose MT images depicted 33% more enhancing lesions and 18% more new enhancing lesions than the single-dose non-MT images. Twenty-nine percent more lesions were detected on triple-dose non-MT images than on single-dose MT images. The combination of a triple dose of contrast material and MT did not produce any significant change in detection of enhancing lesions as compared with a triple dose of contrast without MT. CONCLUSION: The use of a triple dose of contrast material is the best approach to maximize the sensitivity of enhanced MR imaging.     

Measuring resolution in the contrast domain: the small letter contrast test

BACKGROUND: Recent evidence suggests that small letter contrast sensitivity (CS) is more sensitive than visual acuity (VA) to defocus, luminance, binocular enhancement, and visual differences among pilot trainees. It would be valuable to make this test available for general use. We developed a hard copy (letter chart) version called the Small Letter Contrast Test (SLCT) and evaluated its sensitivity and reliability in comparison to standard vision tests. METHODS: The SLCT has 14 lines of letters with 10 letters per line. The letters are of constant size (20/25 or 4/5 at 4 m), but vary in contrast by line in 0.1 log steps (0.01 log units per letter). Normal room illumination is used. The SLCT was evaluated in 16 subjects under various conditions (spherical and astigmatic blur, low luminance, 2 eyes vs. 1 eye) to determine test sensitivity and reliability, and in patients with clinical conditions. Scores were compared to those obtained with standard tests of VA (Bailey-Lovie) and CS (Pelli-Robson). RESULTS: SLCT scores were similar to previous measures, and retest reliability was one line. The SLCT was more sensitive than VA to spherical and astigmatic blur, low luminance, and vision with two eyes vs. one eye. Greater sensitivity of the SLCT endured despite correction for variability. The SLCT was more sensitive than standard tests to visual loss from early cataract, keratoconus, corneal infiltrates, edema, and amblyopia. CONCLUSIONS: The SLCT is a sensitive, adjunctive test, which complements existing measures of VA. It can reveal subtle visual deficits that may be undetected by standard clinical techniques. The SLCT should prove useful for monitoring vision in refractive surgery, corneal and macular edema, optic neuritis, and for selection and evaluation of candidates for occupations requiring unique visual abilities like aviation.