Comparative study of cellulose isolated by totally chlorine‐free method from wood and cereal straw

Highly purified cellulose preparations were obtained by pretreatment of dewaxed barley straw, oil palm frond fiber, poplar wood, maize stems, wheat straw, rice straw, and rye straw with 2.0% H₂O₂ at 45°C and pH 11.6 for 16 h, and sequential purification with 80% acetic acid–70% nitric acid (10/1, v/v) at 120°C for 15 min. The purified cellulose obtained was relatively free of bound hemicelluloses (2.3–3.2%) and lignin (0.4–0.6%) and had a yield of 35.5% from barley straw, 39.6% from oil palm frond fiber, 40.8% from poplar wood, 36.0% from maize stems, 34.1% from wheat straw, 23.4% from rice straw, and 35.8% from rye straw. The weight‐average molecular weights of the purified cellulose ranged from 39,030 to 48,380 g/mol. The thermal stability of the purified cellulose was higher than that of the corresponding crude cellulose. In comparison, the isolated crude and purified cellulose samples were also studied by Fourier transform IR and cross‐polarization/magic‐angle spinning ¹³C‐NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 322–335, 2005     

一种短波宽带定向耦合器的设计

根据变压器串并联同时耦合的原理，提出了一种利用三线变压器魔T和传输线变压器构成定向耦合器的方法，给出了设计原理，设计制作了一种短波宽频带、大功率定向耦合器。并对其参数进行了理论计算和实际测量，测试结果与理论分析吻合，满足设计要求。经过实际应用，验证了设计方法的可行性。     

Effects of subliminal sympbiotic gratification and the magic of believing on achievement.

The present experiment examined the effect of a subliminally presented symbiotic gratification and a magic of believing message on academic achievement. Graduate students were randomly assigned to one of the two experimental message conditions, or to a control message condition, and received on the average 12 sessions, 10 exposures per session, of 4-msec visual subliminal presentation of one of the three messages. Each session occurred immediately prior to a lecture in either a statistics or a measurement class. Each of the courses was taught in a traditional manner by the regular faculty, who were naive regarding the experimental conditions. Objective final examinations for each course revealed statistically significant differences in favor of the symbiotic gratification experimental condition over the control condition. No differences were obtained between the symbiotic and magic of believing conditions. Research and clinical implications of the findings are also explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

钝头体三维绕流问题的数值模拟

根据ＴＶＤ有限体积法数值模拟了钝头体空间来流绕流问题，并绘制了不同旋转平面（子午面）沿钝头体轴向的压力分布图，反映了空间任意来流在弹体任意子午面其参数的不对称性以及压力、密度和速度特征．     

高射频武器排壳装置的动力学仿真分析

针对某高射频武器未击发弹在排壳通道内的运动,运用Pro/E软件建立了实体模型,将其导入ADAMS进行了动力学仿真分析,得到了该弹在排壳通道内的运动规律;并对排壳通道的最薄弱环节,对最大撞击力点进行了强度校核,结果表明该排壳通道满足强度要求。文章为排壳通道的结构优化设计及复杂碰撞运动的求解提供了一种较为简洁的方法,对工程运算及设计具有一定的参考价值。     

某特种弹头涂双色工艺研究及应用

为了满足GJB3911<通用弹药标志细则>的有关规定,须对某特种弹头涂双色标识.但在现有生产条件下,弹头尖部涂双色标识难度很大,长期以来都存在着涂色质量不稳定、不能连续批量生产等问题.针对本公司某特种弹头必须涂双色的特定要求,利用现有生产场地及设备,对其相关的工艺、涂料、设备进行了深入的研究和改进,试验获得巨大的成功.新工艺实施后,涂双色的弹头产品质量稳定可靠,满足连续自动的机械化生产,在短期内保质保量地完成了全年的生产任务.至此,彻底解决了弹头涂双色的工艺技术问题.大批量的生产实际表明:改进后的弹头涂双色工艺、设备是非常成功的,对同类问题的解决提供了参考的依据.     

圆柱形带壳推进剂装药枪击响应特性

为研究某圆柱形带壳推进剂装药的枪击响应特性,设计了一种12.7 mm子弹撞击试验。利用高速摄影机记录带壳装药在子弹撞击下的响应过程,并测试不同距离、方位处的空气超压及壳体破片速度,同时进行带壳装药在理想爆轰条件下的数值计算,得到了带壳装药的能量释放率。一共开展了四次圆柱形带壳装药的枪击试验,前三次装药发生了爆燃反应,第四次几乎无反应。结果表明:子弹撞击位置对圆柱形带壳装药的反应和能量释放率有较大影响,当子弹垂直入射带壳装药轴线后,推进剂发生点火、冒烟、熄火和低压燃烧的时序响应,其相对能量释放率为1.146%;而当子弹撞击位置偏离轴线一定距离时,推进剂几乎无反应,其相对能量释放率仅为0.473%;推进剂的反应对壳体破片有加速效应,带壳装药发生爆燃反应时的破片速度可达428.6 m·s~(-1),而几乎无反应时的最高破片速度仅有70.1 m·s~(-1)。     

Human uncertainty in explicit user feedback and its impact on the comparative evaluations of accurate prediction and personalisation

ABSTRACT

In this article, we report on the lack of reliability of explicit user feedback and its interpretation in the light of system evaluation. It is known, that given feedback strongly depends on the situational context. But also when many contextual factors are held constant, user feedback still proves to be unreliable. This impacts the evaluation of predictive algorithms since it is not clear whether a deviation between a user response and its corresponding prediction can be seen as a flaw by the system or just as usual ‘human uncertainty’. As a result, the perspective on the evaluation of adaptive systems basically changes. The main goal of this article is to demonstrate that simply increasing the amount of explicit feedback is not the key to sustainable system design innovation, as long as that information is not appropriately evaluated. To this end, we will exploit a novel probabilistic approach of processing user feedback and identify biasing effects on accuracy metrics, error probabilities for system rankings as well as natural limitations of evaluation. Finally, we will discuss possible solution strategies and give advice for handling explicit user feedback that is associated with uncertainty.     

弹序管序识别装置研究

弹序管序识别装置是多管炮立靶精度测试系统的一个子系统,当多管炮齐射连发时,该装置将从炮口射出的一连串弹丸按时间先后排队,并判明每发弹的管序本文介绍了弹序管序识别装置的方案设计和主要电路工作原理