面向对象的图形用户界面的开发

本文描述了一种具有事件（消息）驱动机制的面向对象的图形用户界面的研制。该图形用户界面的开发，是基于ＢｏｒｌａｎｄＣ＋＋的ＴｕｒｂｏＶｉｓｉｏｎ产品，利用Ｃ＋＋语言的继承性和多形性，建立了可创建图形用户界面的类和其它数据结构。     

飞行的天使舞动的精灵

天上的北极星在夜晚的星空中不停的闪烁,像要把自己身上的那些光芒全部撒向大地.北方--自古以来都是方向的指引者,不管你身在何处,它都终年不变的为你指明方向.就像她们一样,追着自己舞动的梦从西北的兰州到东北的沈阳,也逃脱不了这股神秘的束约.初识这对双胞胎姐妹是在朋友开的影楼里.那天正巧赶上她们第一次照制服照片,闪光灯下羞涩的表情中隐约透露出一丝兴奋,这大概是她们身上天生就有的表演分子细胞又一次在新环境下的重合反应.     

关于法的本质属性的探讨

关于法的本质属性问题,我国法学界的看法尚不统一。本文作者认为,法的本质属性具有两个层次:一个是国家意志性、国家强制性和特殊规范性,它们属于法的“不甚深刻”层次的本质属性,一个是阶级性,它属于法的“更深刻”层次的基本属性;法的本质属性是上述各层次、各方面本质属性的有机结合和统一。本文对法的各种(或各方面)本质属性以及两个层次本质属性的关系,作了比较具体深入地分析和论述。同时,对法的某些属性是否本质属性,作了简要分析,提出了自己的看法。另外,对前一个时期反映出来的一些非马克思主义法学的观点,也作了必要的辨析和澄清。     

思想的活力 创新的源头

理论由实践赋予活力。毛泽东思想作为科学的思想理论体系,曾在中国革命事业的重大关头,不断地开创过一个又一个的新局面,今后它仍将指引我们胜利前进!邓小平说:“毛主席最伟大的功绩是把马列主义的原理同中国革命的实际结合起来,提出了中国夺取革命胜利的道路。应该说,在六十年代以前或五十年代后期以前,他的许多思     

永恒的主题 永恒的追求

在民航各企业制定的2004年工作思路和奋斗目标中,安全和效益依然是共同的主题,“年年岁岁花相似”。但发展是无止境的,而且与以往相比,在2004年的新形势下,民航在安全和效益方面面临的任务压力更大,也具有更高的挑战性。不平凡的2003年,中国民航经历了几多风雨,也收获了几多喜悦。在经受了SARS的考验之后,全行业努力实施“蓝天振兴计划”,在安全和效益上都实现了新的跨越,特别是在飞行安全方面创造了新的记录。但新的记录也意味着新的高度和挑战。正如杨元元局长在春节之前国务院新闻办召开的新闻发布会上所指出的,对民航而言,安全工作永…     

企业文化建设的的关键环节

企业文化研究不仅是个理论问题,更是个实践过程。本文就企业文化建设的关键环节进行了深入讨论,以期增强企业文化建设的可操作性,对企业的管理活动起到实际的指导作用。     

行列式的值等于零的充要条件

利用行列式的一些性质，推导出行列式值为零的充要条件，提出一种简捷的解题方法。并举例说明其应用。     

最适用的才是最好的

随着“航线经理制”和“客户经理制”在南航股份公司的全面推广,许多分(子)公司已经从中尝到了甜头,充分认识到开展“两制”的必要性和重要性。那么,如何让“两制”改革更好地实现促进效益持续增长的最终目标呢?笔者认为,只有做到避免两个极端,掌握一个原则,才能在不断创新、不断超越自我中实现新的腾飞。第一种极端就是盲目求大、任务过高。有些公司在“两制”试行时,盲目求大,希望进行一次彻底的营销改革,实现一步到位,把所有的“宝”都押在了“两制”上,但效果却不理想。因为,这样的改革往往对目标的科学性以及“两制”人员的业务素质有…     

科学的事业伟大的精神

1903年12月17日,莱特兄弟成功完成人类第一次动力飞行,翻开了航空史新的一页. 回顾航空工业百年发展,试飞的作用举足轻重.今日航空技术的发展和飞行安全水平的提高都离不开百年来试飞人为之付出的努力,有时甚至是生命的代价.     

我的机场我的梦

<正>"职工电影梦系列"所走过的三年时光,汇聚成上海机场人圆梦舞台的最强光,催生出了一批热爱机场、热爱艺术、热爱生活的职工"明星"。当镁光灯渐渐暗去,那些追逐"机场梦"的脚步依旧铿锵!4月23日晚上,当3名农民工身着礼服像电影明星一样亮相梅赛德斯-奔驰文化中心的红地毯时,全场观众报以热烈掌声。当晚,由上海机场集团组织拍摄、机场职工自己主演的"职工电影梦系列(第三季)"影片《深蓝》首映式在此举行。作为创新职工文化建设载体的有益尝试,近年来上海机场集团组织拍摄、并由职工出演了反映自己工     

Interference torque of a three-floated gyroscope with gas-lubricated bearings subject to a sudden change of the specific force

A numerical study is carried out to investigate the influence of a sudden change of the specific force on a three-floated gyroscope with a rotor supported on gas-lubricated bearings.The interference torque is calculated to evaluate the influence by modeling the transient behavior of the rotor-bearing system. In combination with dynamic equations of the rotor displacement,the Reynolds equation is solved on the surface of spiral-grooved conical bearings. It is assumed that a steady state has been obtained with a constant specific force, and then the specific force is suddenly changed and maintained constant after that. Responses of the sudden change are obtained by solving the equations. Numerical results show that the direction of the sudden change of the specific force is the main factor which influences the interference torque curve. With a sudden change along the input direction, the interference torque fluctuation has a constant frequency and a decreasing amplitude. With a sudden change along the output direction, the interference torque fluctuates in a small range. With a sudden change along the spin direction, the change of the interference torque combines a fluctuation and a gradually-changing quasi-equilibrium value. This study provides a supplement to the steady-state error model of the three-floated gyroscope.     

Detection of chi-square fluctuating targets in arbitrary clutter

In a recent paper, general expressions were derived for the density and cumulative probability functions of the amplitude of a linear matched-filter output given a nonfluctuating target in a clutter-limited environment. These expressions were based on the clutter amplitude density function. The results are extended to calculate the cumulative probability function of the output of a linear matched filter used to detect a chi-square fluctuating target in a clutter-limited environment. The resulting method is applied to a common radar clutter model, and experimental sonar data.     

Optimum FFT-based frequency acquisition with application toCOSPAS-SARSAT

In the case of a single sinusoid or multiple well-separated sinusoids, a coarse estimator consisting of a windowed Fourier transform followed by a fine estimator which is an interpolator is a good approximation to an optimal frequency acquisition and measurement algorithm. The design tradeoffs are described. It is shown that for the fine-frequency estimator a good method is to fit a Gaussian function to the fast-Fourier-transform (FFT) peak and its two neighbors. This method achieves a frequency standard deviation and a bias in the order of only a few percent of a bin. In the case of short-time stationarity, for a moderate number of averages and for an adaptive threshold detector, only between 0.5 and 1 dB is lost when averaging is traded off for FFT length, in contrast to the asymptotic result of 1.5 dB. The COSPAS-SARSAT satellite system for emergency detection and localization is used to illustrate the concepts. The algorithm is analyzed theoretically, and good agreement is found with test results     

The Measurement of Echo Direction in a Phased-Array Radar

For a planar-array antenna with a monopulse feed horn, this study describes a simple algorithm for the determination of the direction of target echoes. Antenna pattern measurements of the array indicate that the direction sines of a received wavefront can be independently obtained with one simple relation between a normalized difference channel output and a direction sine. This paper determines the accuracy of the algorithm.     

A comparative study on acoustic damping induced by half-wave, quarter-wave, and Helmholtz resonators

The damping characteristics of three-type resonators, a half-wave, a quarter-wave, and a Helmholtz resonator are studied experimentally by adopting linear acoustic test. A quantitative acoustic property of sound absorption coefficient in a model enclosure with the resonators is measured and thereby, the acoustic-damping capacity of a resonator is characterized. For a comparative study on acoustic damping, the damping capacity of a half-wave resonator is compared with that of the other resonators. A half-wave and a quarter-wave resonators have the same damping mechanism, but a quarter-wave resonator has much larger damping capacity than a half-wave resonator with the same diameter of a single resonator. It is found that shorter length of a resonator has the advantage of longer one with respect to the damping capacity. The damping capacity of a Helmholtz resonator increases with cavity volume and does as the orifice length decreases. A Helmholtz resonator has the highest damping capacity of three-type resonators and a half-wave resonator has the lowest. Besides, a Helmholtz resonator requires the smallest number of resonators for optimal damping. The design criterion of each resonator on the optimal damping is provided by the normalized parameter of open-area ratio and the similarity behavior for the optimal damping is observed for various enclosure diameters.     

液体冲压发动机控制系统半实物仿真

运用小偏离线性化理论和Willoh方法，建立了液体冲压发动机和弹体动态数学模型。动态数学模型在微型计算上一体化运行，形成液体冲压发动机／弹体一体化实时数字仿真器。实时数字仿真器通过输入输出接口与液体冲压发动机的实际控制系统进行联接，组成液体冲压发动机、弹性和发动机控制系统半实物仿真系统。对冲压发动机飞行马赫数和控制 系统供油量的半实物仿真结果表明，系统能满足研制工作的需要。     

Measurement of Distributed Targets with the Random Signal Radar

A model of a distributed target as a collection of independent, Poisson distributed point scatterers or scattering centers in a range-velocity target space is introduced and is characterized by a deterministic function called the ?scatterer density function.? This function is the density of the point scatterers in the range-velocity space and can be estimated in a relatively straightforward manner by any radar having adequate resolution in both range and velocity and no ambiguities in the region occupied by the distributed target. The use of the random signal radar with a correlator receiver is considered here and the statistical properties of the correlator output, when the return signal is from a distributed target, are derived. It is shown that the spectral density is simply related to the scatterer density function. The technique is illustrated by an example in which the target is a tornado modeled as a cylinder with constant angular velocity. The example suggests that is a possible to remotely estimate the radar cross section per unit volume as a function of distance from the center of the tornado.     

Dynamics and de-spin control of massive target by single tethered space tug

This paper investigates the dynamics and de-spin control of a massive target by a single tethered space tug in the post-capture phase. The dynamic model of the tethered system is derived and simplified to a dimensionless form. Further, a decoupled PD controller is proposed, and the local stability of the controller is analyzed by linearization technique. Parametric studies of the dynamics and de-spin control of a massive target are conducted to characterize the dynamic process of de-spin with the proposed control law. It is shown that the massive target can be de-span by a single and small space tug with limited thrust within finite time. The thrust tangent with the tether de-spins the target while the thrust normal to the tether prevents the tether from winding up the target. The tether length has a positive contribution to the de-spin of a target. The longer tether leads to a faster de-spin process.     

止裂孔尺寸对止裂效果影响的研究

当航空器结构在航线使用过程中出现疲劳裂纹损伤时,通常在裂纹尖端打止裂孔进行临时性修理。通过理论分析和计算及试验分析,研究了止裂孔尺寸对止裂效果的影响。结果表明,当航空器结构出现疲劳裂纹损伤时,采用5.57～7.14mm直径的止裂孔进行止裂修理,止裂效果较好;当止裂孔直径为6.35mm时,止裂效果最好。     

直升机燃油系统地面模拟试验中试验台转角与油面角的关系

为了在直升机燃油系统地面模拟试验中准确地模拟油面角，本文介绍了试验台转角与油面角的关系，并给出了转换结果，同时，提出了一种用油箱内增压来模拟过载的设想，使在模拟试验时，油泵供油更趋真实，通过简化计算，给出了确定气压力的方法和判断依据。